Yes, community support is key, which means choosing a phone that is somewhat maintainable and that has sold/will sell to a lot of people.
I am looking around because my Nexus 4 died, and I decided to sell my warranty replacement. I bought it because I thought it would be great for updates, but the official updates were buggy, and the introduction of Google Services updates via the Play Store made the timeliness of updates less important (getting them some time is still important).
In the end, I couldn't deal with the battery life.
I don't game on my phone, so I am thinking I would like to pick up a quad core A53 (for the 64 bit-ness and ARMv8 instructions including AES encrytion acceleration) with 2GB RAM, LTE, 16GB flash plus SD card support, a decent camera (including low-light), decent noise cancellation on calls, and a removable battery.
None exist.
The Huawei Ascend G7 comes close, but is a bit bulky (5.5" screen), and the battery is non-removable, although large at 3,000 mAh, and in-call noise isn't great. I'm not sure it will sell all that well either, so developer support is questionable.
I have pre-ordered the Saygus V², which looks great on paper, but it lacks a 64-bit SoC and is expensive after tax in the UK. I may cancel, depending on whether I see a review before it is due to ship.
Also interested in the Asus Zenfone 2, but have concerns over how supportable that will be, given it has to rely on proprietary code translation to handle apps written in C.
I had hoped the Moto G (2015) LTE edition would be on A53s, but Motorola/Lenovo have stuck with Snapdragon 400, which is crazy.
So I don't like anything really in terms of longevity. In those circumstances, it's better just to cheap out on a transitional phone.
Oh, I would like dual SIM dual active as well, but I have lost hope of getting that along with everything else.
Edit: Been coming here for over fifteen years, but I forgot my password and my sign-up email is dead now.