They will fall out over ego
And it will happen in Q1 of next year.
There isn't a room big enough for both their egos, and him hanging around Trump trying to tell him who he should appoint and everyone else what they should do is going to start wearing thin. Probably the first time Musk takes credit for something is when it will happen.
I don't think he's realized that everything good that happens is because of Trump, and everything bad that happens is someone else's fault - and if he decides to pin the blame on you, you aren't allowed to contradict him. All the hangers-on who didn't learn that lesson in time were ejected from his orbit and became persona non grata.