How is this not the world we already live in?
Every agreement, obligation, promise, or contract I've read from my major tech 'partners' professionally and personally has had a clause that they can change it at any time with no prior notification.
That being said, at least they include the clause. If this promise had been phrased as, "we won't link with Google products, but we might in the future", I would honestly feel a bit more charitable towards them. It wasn't.
DeepMind went out of its way to describe this not just as a temporary promise, but as a legal one.[0] In their words, "...data will never be connected to Google accounts or services, or used for any commercial purposes like advertising or insurance. Doing so would be completely impossible under our NHS contracts and the law".
That is a full step beyond the crappy TOS that most companies use, and statements like that were given to ease consumer concerns and make it easier for DeepMind to form deep relationships with hospitals.
One other thing to note outside of legal obligations or technicalities is that even if you don't think Google did anything different from the companies you're talking about, companies who do 180s on their TOS still lose trust. The trust loss is separate from the legality.
I don't know if you can go to Google and say, "legally, you shouldn't be allowed to link your product," I'm not a lawyer. I do know that we as consumers and engineers should instinctively distrust any future promises that Google makes about privacy.
If what they're doing is legal, I'm still going to call them out for being untrustworthy and dishonest. Their earlier statements are still lies.
[0]: https://twitter.com/MalcolmMoore/status/1062394654702927873
So the new promise is "Patient data remains under our NHS partners' strict control, and all decisions about its use will continue to lie with them." Except I can think of at least two or three good reasons off the top of my head why Google could renege on that without breaking the spirit of their promise too. Maybe Google decides that the information will be more secure on their servers, and the original point was to make it more secure anyway, right?
Yes, Google's original promise was kinda arbitrary and over-strict. But the way you build trust is you keep promises, even if they're arbitrary. When Google says they're not going to do something, they should not do it. Otherwise, nobody will trust them in the future when they say they're not going to do other things. Nobody wants to live in a world where we have to second guess what the intent is behind everything a company promises and are only able to hold them to that.
If Google can't keep its promises, then it shouldn't have made any promises in the first place. It should have just given a milk-toast answer like, "we care about privacy", which would have communicated exactly the same information without deceiving customers into thinking that there was an actual line in the sand somewhere.