There's no leaving Twitter, in my opinion. Its the only game in town. That said, I sincerely hope there is a fracture here. An ecosystem with many smaller platforms seems far healthier to me.
My conspiracy theory is that Musk is buying Twitter mainly so he can extort Trump for something in exchange for readmitting him. Like telling his base to buy Teslas.
I don't think it will be that obvious/simple. Tax breaks, anti-union laws, incentives to build new plants in red states... or something even smaller will be all it takes.
Trump has only ever posted a single time on Truth Social, a generic coming soon message, and it probably wasn't even him. He doesn't give a shit about it. He doesn't even know its name, apparently: https://www.businessinsider.com/video-shows-trump-struggling... It's best to think of Trump's role with Truth Social as a disinterested mascot. Even your basic paid shill would be doing a much better job of promoting/using it.
Trump loves Twitter, and would be back on it in a flash if allowed to do so.