1 - The developers funded by Apple will likely do okay, but the alleged payment schemes from subscription fees is unlikely to make short one & done experiences any real money. They are allegedly rewarding duration of play over the flat upfront fees typical on other subscription services (e.g. GamePass, PSNow, GwG, PS+ etc). Similar to how Spotify rewards plays.
2 - I suspect not as many as Apple think, and Apple typically changes its mind on "gaming initiatives" with the seasons.
But "netflix for games" is compelling. Lately, the traditional one & done "premium" app is a harder sell on iOS than it has been in the past - the demographic's changed, promotion by Apple has changed, and the competition for eyeballs + dollars is fierce. Sub services can be appealing, I just don't know if iOS is that market.
3 - ...
4 - No.