If you've been caught up in all of the Pixel news today, then you might have overlooked something in the specs page. It would appear that Google is extending its software update promise from two years to a minimum of three years. That's fantastic.
Security patches have had a three-year promise for a while now, but adding in OS updates to that is swell. This may have something to do with Project Treble and the extension of the Linux kernel LTS timeline. Whatever the reason or cause, it makes a Google phone more enticing for the regular user.
If I was Google, I'd certainly be playing this up, not hiding it in a specs sheet. If the minimum OS update schedule is three years (or more), that'd make the Pixels much more competitive with the iPhone from a support standpoint. And based on the wording of the promise, I don't think this is a typing error — if it said something like "3 years of OS and 3 years of security updates," I'd be more dubious.
Google has updated its support page to clearly state that the Pixel 2 will get 3 years of software updates and 3 years of security updates. It also published this table below for an easy and clear look at the minimum support dates of each device in the Pixel line.
If Android releases continue at the same pace and schedule (August of each year), then you're looking at getting Android P in 2018, Q in 2019, and R in 2020 on your Pixel 2 and 2XL. That's 4 versions of Android on the same device, provided the battery lives long enough to tell the tale. The first-gen Pixel will be cut off next year, so beside launching with Nougat and getting Oreo, it will see P but not more.