That game already exists, and it's called MK9 or MK2011 or simply MK.
In the future, every 10 years or so, there will be a compilation game.

we had
MK: trilogy (1996)
MK: armageddon (2006)
MK: 2011 (2011/12)

expect the new compilation in 6/10 years from now

I'm honestly begging for another MK clash game. Aside from Armageddon's glaring gameplay issues, it's biggest problem was being canon. Trying to find some bullshit excuse to bring back everybody was a disaster waiting to happen.

The Tekken Tag games are a love letter to fans, which is what MKA should've been. The Tekken Tag games know what they are, and that is a giant fan service. Just a reason to bring back all the fighters so everyone can have their favorites back.

I'd love to see an MKA2 someday though. (Non canon of course) MK has finally hit it's stride gameplay wise, the presentation has never been better, and the new characters to have appeared since MKA would be cool to see fighting characters who may never appear in MK again.

That said, I'm not sure if we'll see something like that. MKA had 60+ characters, and MKX is looking to have more than 10 new characters. That's over 70 and that's not even including Skarlet. Balancing that game with that many characters would be a nightmare.

Yeah I think a new "all characters ever" game would be amazing, they just need to not try and make it canon. If anything it could just be a huge "what if" story, it would be a lot of fun, especially if it was 2.5D.