Of course, my 5a will only be paid off in another 19 months, at which point a hypothetical Pixel 7a will presumably be available for upgrading, hopefully also with a similar subscription plan, but meanwhile whether the 6a even has a subscription plan is an indicator of what the offerings will be in another year and a half.
I am glad that the 6a has a Tensor chip (that's the one significant limitation of the 5a compared to the rest of the current lineup), so whatever else, I can be reasonably certain that the phone upgrade will have one too.
I find the urge to conduct kremlinological analysis somewhat annoying, but given that my subscription agreement just says that I will have an opportunity to upgrade at the end of the payment plan, with no indication as to the price or value of that upgrade, it is hard not to worry.
It is interesting though that the present value of a subscription hardware purchase is now hinging in part on the future upgrade opportunity (and in the sense of replacement with a new version rather than expansion with add-on hardware) just like software.
That said, even if that future upgrade opportunity turns out to be crap, I'll only be disappointed rather than feeling burned. After all, a sizable discount and an interest-free payment plan on a solid mid-level phone was a decent deal regardless.