On 17 August, Google's Android development team commenced the release of the official final Developer Preview update along with Android 6.0 SDK (Software Development Kit) to programmers.

The search engine giant is expected to roll out the final public version with the rumoured LG's Nexus 5 (2015) aka Bullhead and Huawei Nexus aka Angler late September or early October.
Once the devices are released, the company is expected to deploy the new OS to its previous generation Nexus, and later release it to devices of Google's OEM (Original Equipment Manufacturer) partners such as Motorola, Sony, Samsung, HTC, Asus, among others.
So far, HTC is the only company which has confirmed that the new update will be released to the One M8. Samsung has vaguely indicated the new Galaxy S6 series will be the first among the Galaxy S series to get Google's newest sugar-treat update
To provide a better perspective, we have a listed the flagship smartphones, which are mostly like to get the new Android 6.0 Marshmallow.
Google Nexus series:
One of the main perks of owning a Nexus series is the satisfaction of getting the latest updates before owners of other branded phones get it.
We are certain that the Google LG Nexus 5 (2013), the Motorola Nexus 6 (2014) and also the Google Edition series of Samsung, Sony and HTC devices will also get the update, shortly after the release of v6.0 Marshmallow.
There is a possibility that Google might ditch the Nexus 4; since the final developer preview Android M firmware hasn't been released to the 2012 device. As of now, it is only available to the Nexus 5 and the Nexus 6
Google Android One series:
Android One series are an official affiliate of Google, so they will be one of the first smartphones to get the latest update. But this myth was busted last year, because Google took almost three months to release the update to Android One series- Micromax Canvas A1, Spice Dream Uno and Karbonn Sparkle V in India. The good thing was that the company released the latest 5.1 Lollipop, directly skipping three incremental updates (5.0, 5.0.1 and 5.0.2).
But things are about to change as Google is making arrangements to ensure there is no delay this time. Two weeks ago, it released second generation Android One series Lava Pixel V1 in India, followed by Infinix Hot 2 launch a few days ago in Africa (Ghana, Ivory Coast, Egypt, Kenya and Morocco).
Google is expected to roll out Android M to Micromax Canvas A1, Spice Dream UNO, Karbonn Sparkle V, new Lava Iris Pixel V1, Nexian Journey One (Indonesia) and other Android One series launched in South East Asian markets and Africa.
Motorola:
Google's former mobile division, Motorola, has a good reputation of promptly releasing the new update without much tweaks as soon as it gets hold of Google's Android OS source code.
Motorola will release the new Android M starting with Moto X Style (aka Pure Edition in US), Moto X Play, Moto X (2014), Droid Turbo (aka Moto Turbo in India), Moto G (2nd and 3rd Gen) by the end of December 2015 or early 2016.
Lenovo:
Motorola's parent company, Lenovo, is expected to release the Android M update to K3 Note, Vibe Shot and to the recently unveiled ZUK Z1.
HTC:
This year, HTC launched a slew of top-end devices, including One M9, One M9 Plus, E9, E9 Plus. All the devices are certain to get the new Marshmallow update.
Last month, a HTC One M8 owner, on Twitter candidly asked HTC US head, Mo Versi, whether the company will release the new Android M series to his device. To his surprise, Versi confirmed that the device will indeed get new OS update.
So, the HTC One M7 (2013) and some mid-range and budget Desire series phones, including those released in mid-2014, will not get the update.
Samsung:
Samsung, as always, is expected to release the Android M update in reverse chronological sequence starting with the latest devices such as Galaxy Note 5, Galaxy S6 Edge+, Galaxy S6 (S6 Edge), Galaxy A8, Galaxy Note 4, Note Edge and Galaxy S5. There is a possibility Samsung might also deploy the update to mid-range Galaxy A5, A5 and the Galaxy E series as well.
Sony:
In 2014, Sony had announced to release 5.0 Lollipop to all of its Xperia Z series in early 2015, but failed to meet the deadline. Despite facing troubles with bugs riddled source code, it managed to complete the feat in May this year.
Now with the announcement of Android 6.0 Marshmallow, many will be curious to know whether Sony will release the latest OS to all its Xperia Z series. Well, the company is not likely to do an encore on all the Z series, as some of the devices featured in Lollipop update list are now more than two years old.
Based on 18 months' obligatory software update service contract with Google, Sony is certain to deploy the Marshmallow OS to the recently released Sony Xperia M5, C5 Ultra, Xperia Z3 Plus (aka Z4).
Other devices which are likely to get the software are Xperia Z3, Z3v, Z3 Compact, Z2, Xperia Z Ultra GPE (Google Play Edition).
LG:
Besides the LG Nexus 5, the company is expected to release the new Android 6.0 Marshmallow OS to G4 and also to G3, since the device was launched in 2014 and is yet to complete the 18-month life cycle.
Asus:
Since the new Zenfone 2 series (ZE551ML, ZE550ML, ZE500CL) and new Zenfone 2 Deluxe (ZE551ML), Zenfone 2 Laser (ZE550KL/ZE601KL), Zenfone Selfie (ZD551KL) were released this year, they are certain to get a taste of Google's new sugar candy flavoured OS.
OnePlus:
Both the 2014 model OnePlus One and the recently released OnePlus 2 are most likely to get the update. It is expected to come via custom skin OxygenOS/HydrogenOS update.
Xiaomi:
Just days ago, the Chinese company unveiled the new MIUI 7 based on the Android 5.1 Lollipop. Xiaomi will release this update to Mi4, Mi4i, Mi3, Redmi 2, 1S, first generation Redmi Note (3G & 4G) starting on 24 August.
Since Android M is expected to be released in September/early October, Xiaomi might take two or three months to release this version, probably in the form of MIUI v8.0 to Xiaomi Mi 4i, Redmi Note 2 and other devices in December.
Huawei:
Huawei is expected to launch the new 2015 series Nexus phablet with Android M OS out-of-the-box later this year. The company, which is now in the list of the world's top 5 smartphone makers, will definitely try to bring the new Marshmallow OS to a large number of its devices, most probably to the Ascend Mate 7, Honor 6 , 6 Plus so that it retains the loyalty of fans.
Cyanogen Powered Devices
Many devices running cyanogen were launched in the 2014-15's like the OnePlus One and Yu Yureka and the YU Yuphoria! So they will definitely get the update!
[Disclaimer: This list of phones we have predicted to get 6.0 Marshmallow update is based on previous Android OS release patterns, so this is not a confirmed list, but a catalogue of probable devices. And some handsets might be missed in this table due to vast number of devices launched in late 2014 and 2015. Even the update release time-line can also get pushed, as the deployment is prerogative to the individual company. Stay tuned as we will be updating this, as and when it develops]
List of Smartphones Likely to get Android 6.0 Marshmallow OS:
| Smartphone Brands | Likely to Get Android 6.0 Marshmallow OS | May or May-not get the Android 6.0 Marshmallow OS |
| Google Nexus | Nexus 5, Motorola Nexus 6, Nexus 7 (tablet) | Nexus 4, Nexus 7 (2012), Nexus 10 (tablet) |
| Google Android One series | Micromax Canvas A1, Spice Dream UNO, Karbonn Sparkle V, new Lava Iris Pixel V1, Nexian Journey One (Indonesia) and other Android One series launched in South East Asian markets and Africa | -------------------- |
| Motorola | Moto X Style, Moto X Play, Moto X (2 Gen), Droid Turbo (aka Moto Turbo in India), Moto G (2nd Gen & 3rd Gen), Moto E (2nd Gen), | Moto X (1st Gen), Moto G (1st Gen), Moto E (1st Gen), |
| Lenovo | K3 Note, ZUK Z1, Vibe Shot, | Vibe Z2, Z2 Pro, A7000 |
| Samsung | Galaxy Note 5, Galaxy S6 Edge+, Galaxy S6 (& S6 Edge), Galaxy Note 4, Galaxy Alpha, Galaxy S5, Galaxy A8, A7 | Galaxy A5, A3, Galaxy E-series |
| HTC | HTC One M8, HTC One M9, M9 Plus, E9, E9 Plus, One E8 | HTC Desire Eye, Desire 820 series |
| Sony | Sony Xperia M5, C5 Ultra, Xperia Z3 Plus (aka Z4), Xperia Z3,Z3v, Z3 Compact, Z2, Xperia Z Ultra GPE (Google Play Edition) | Xperia Z1 |
| LG | G3, G4, Flex 2 | G2, G2 Pro, G Flex |
| Asus | Zenfone 2 series, Zenfone 2 Laser, Deluxe, Zenfone Selfie | Zenfone 6, 5, 4, |
| OnePlus | OnePlus One and OnePlus 2 via new OxygenOS/HydrogenOS skin | ---------------- |
| Xiaomi | Xiaomi Mi4, Mi 4i, Mi Note, Mi Note Pro, Redmi Note 2, Redmi 2 (& Prime) | Redmi Note (2014), Redmi 1S |
| Huawei | Ascend P8, Mate 7, Honor 6 Plus and more |
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| iBerry feat. Elephone | Auxus Prime P8000 aka Elephone P80000 (confirmed to get Android M) |
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