The thing you don't seem (or don't want) to understand is that for ANY subscription-based model to be able to keep people subscribed you need to offer two things: Quality and variety.
Variety: If they only offer GAAS as you say, people who don't like that will just go away.
Quality: If people don't like what they offer, they will just go somewhere else to find it. And no, people will not keep paying "just because is cheap." You yourself have said MULTIPLE times that you just subscribe whenever a game that interests you comes in and then unsubscribe again.
Oh, and Halo is not simply going GAAS. They have said multiple times that the single-player campaign will be "the longest yet." So I ask you, if Sony provides you a satisfying single-player campaign on the next Spiderman, but then they keep adding stuff over the years on top of it, will you see that as a bad thing?
You forgot quantity there. I subscribed for 2 months and finished Wasteland 3, Battletoads, Grounded, Ori and played enough of Flightsim to know that it's not my cup of tea. Now I'm in lockdown, bored out of my mind and staring at 200 games thinking "nope, nope, nope". It's only $10 bucks but I cancelled anyway - because people are cheap bastards like that - waiting for new big releases before I sign up again. For MS to prevent this they'll need 3 things
quantity so every month there are a couple of A or AA games that'll make people wonder "what's next?!"
GAAS games that people can play forever
Or just cut normal AAA games into episodic content
Adding stuff to spider man is not the same thing as what they're doing with Halo. Games like Spider Man maybe get some DLC and then we're waiting for a sequel. With Halo there will be no sequel, they went full destiny on us. Not saying that is bad, we still have to wait and see how that'll turn out. All I'm saying is that they didn't make Halo GAAS because of design choice, they made it like that because of a business decision. And they'll probably do the same thing with most of their IPs.
If they end up offering just those three things, will you keep your subscription?
