I think we all know that the problem of getting updates out lies not with Google but with the manufacturers and carriers. When I upgraded late last year, my new Droid Turbo 2 came with Android 5.x, and I didn't expect to get an update, ever. I was pleasantly surprised when Lenovo/Motorola and Verizon gave me an update to 6.0. But I don't expect to ever get 7.0 on this phone, and it may be awhile before even the most urgent updates to 6.0 get to me. I like Android, so my next phone may be a Pixel; but I'll also be considering switching to an iPhone for about the same price.
With Samsung suffering now from the Galaxy Note 7 battery problems, this would be an excellent time for that company to announce that it will do all the work (for themselves and the carriers) to update al itsl current phones to 7.0 now and 8.0 when it is released -- and then the next two major versions for phone after that. We'd still have to rely on the carriers to actually provide the updates, but with Samsung handling the software revisions for them, they would have little excuse to delay sending out the updates. (Yeah, it would be a lot of work for Samsung engineers; but I believe it would pay dividends in the long run.)