All the tflops and a subscription service ain't going to bring back what made the xbox succesfull.
Action rpg's like mass effect and a earlier release of oblivion was a big score for the x360. In that sense the acquistion of bethesda may not have been a bad idea.
But that ain't the gist of the xbox, it's after all because of the party chat it was considered the bro station. What could bring that back is games that cater multiplayer in an original way.
Look at magic arena for instance, it's hugely popular on the pc, yet it doesn't even have a proper chat function.
Sports fighting games, all we got is ufc. A brawler with an rpg system could be interesting, and no ufc hug central is not what a lot of people are looking for in a sports fighting game.
Vr and ar: did microsoft forget how successfull the wii was, they got tech like the kinect and the hololens. Racing in vr is a thing as well and they also don't have the bad reputation facebook has.
what about the shooter genre, call of duty reinvented itself with warzone, where's the reinvention of halo