I do believe it would be one biggest coin and get on top 100 immediately but i dont think its good think for him to make a coin cause the regulation would be go bad for him and also its not his focus. Better he keep focus on aerospace technology than this kind crypto asset thing.
It will hit top100 immediately, but with the same speed it will be dropped from top when people realize there is nothing behind that coin. In fact that will be simply another speculative asset, and it will cost a lot of money to create it (because it will be from Musk and deva will charge him every mouse movement they make due to his wealth). That is why there is a rare chance Musk will create something.