A single subscription as the main business model would kill most videogame companies so no, thanks.
For the publishers and devs subscriptions are ok when they don't negatively affect game+dlc sales (which is their main revenue source), so are a good idea as something secondary to put there old games that already completed their sales cycle after several price cuts and discounts, because they generate some small extra revenue, that is better than nothing.
To put the games there day one is ok if the platform holder moneyhats them with a fair deal paying enough money upfront, which isn't the case for most subscriptions and games. And there's only a few games selected for that every month, while there are dozens of released games for each platform every month. They wouldn't be able to moneyhat everybody. All these games not selected for not being the cool kid in the class would die.
So no, the current system is better because it allows to have more companies and more game released, and more types of games.
It would be up to the subscription service to figure out how to best sell that service to individuals. They could go with a high priced service knowing that whales were the only target, or they could go for mass market with a price they felt could draw in enough users to make a smaller price work. Or a console could be released that had no individual game sales, just a catalog of games available and a monthly charge for access. The high priced route would realistically be the most difficult to balance revenue with.
The issue with any of these is how is it decided who gets paid what for each game and how badly does that force devs to build towards whatever that criteria may be.
A more curated service, like GP, just makes more sense with devs maintaining a lot more control.
A subscription ruling the market it's an awful idea for both the devs and the players, it only benefits the platform holder. At least on console, looking at the tie ration, on average people buys a game or two per year. So almost nobody would pay an expensive subscripition.
Devs have 0% control in a curated service like GP, because MS is the gate keeper and decide who are the few games released there that month and how much do they pay these devs. All the other 99% of games who aren't selected would dissapear and their companies would die if somehting like GP rules the market.
Even worse if MS decides to pay the devs included in GP in the same way subscriptions like Spotify pay their artists: for download or playtime. That would focus the revenue even more on a few companies, would kill the small and mid sized ones and would change the games to be more like in mobile, basically super simple games full of mind tricks to keep you coming back and grinding for as much as possible, and constantly trying to make you pay microtransactions because they don't get money with the acquisition of the game.
The best for the devs would be to sell the games keeping a very low revenue share for the platform holder as the main revenue source, with opitonal DLC and microtransactions. And as very secondary, subscriptions where they can put the game to generate some extra revenue when the game is pretty old and doesn't generate money anymore from sales/dlc/mtx.