Starfield will be on gamepass forever unless MS sells Bethesda. It's a first party game. No first party game has ever left the service than I can recall, and they are always on it day 1. I've beem jumping between series X and PC with the cloud saves, it's good stuff. Liking it a lot more than Fallout 4, though the UI might be worse in terms of function. I'm just training myself not to be a kleptomaniac, plenty of credits to earn without spending half your session managing junk in the inventory.
MS even goes out of it's way to make sure old shit still works on the newer xboxes so you can always go back and play.
The EA deal might go away at some stage, and the 3rd party guys don't always re-up but you tend to get 6 months to a year at least to finish a game. More than enough, and if it's a game you really want? Well if you still like it after a 6 month unlimited trial spend the money.
It's an expensive subscription, so is the sony one, but it's fantastic deal. I'm down to one, maybe 2 full priced games a year. It's definitely costing Valve a lot of money that I used to spend there. (Not so much sony, since I subscribe to their thing as well).
If I ever find myself not using it, no biggie. Subscription goes in the bin like with all the others.