You’re still in the return window when you are presented with the service ToS.
Serious answer: I do not expect any specific lifetime at all (though legal return period is an obvious floor), but at a bare minimum I do expect (and think should absolutely be mandated by law) that power be intimately tied to responsibility. Ie., it's fine if a hardware vendor decides to retire their cloud services (or OS updates or the like) in 1 year or 10 years or 20 or 30, but IF they cease to support it, THEN they must also remove any technical obstacles to hardware owners pointing it at another service of any kind. So any signing keys required, code, docs/APIs etc. Decide that a given product no longer makes commercial sense for you to produce or support? Sure, fine, it happens. The problem is then ensuring the hardware/software dies with that.
The basic issue is that these places generally want to have their cake and eat it too. They want all the financial power of a monopoly tie-in and feudal rent extraction, but no responsibilities to go with it and the ability to force customers onto new stuff (or nothing). That should be illegal. Honestly, I think any tie-in should be illegal, fully accessible local APIs should be required and any 1st party subscription should earn its place on its merits.
But at a minimum, no one should be able to have it both ways. If they want power over their customers, they should have responsibility proportional to that. And conversely if they go full open source community friendly hackable from day 1 (and are fully upfront about that), I'm fine saying they have very minimal long term responsibility. There can and should be room for many different approaches to the market, but not extractive lock-in.
Google does quite literally owe their shareholders ROI, by law.
Why would one expect them to do anything other than the minimum support period and expense that they can get away with that won’t trigger a class action?
There are no surprises or bait and switch here. Nobody was promised eternal support or updates.
It’s a business, not a charity.