It's all up in the air at the moment, but I hope, like most smart business people that he leaves things as they are for the most part. Or at least introduces a lot more transparency, regular updates about what's going on, future developments and so forth.
From what I been reading, that's not the plan. It seems to me the plan is to do a token swap and move Steem(it) over to the TRON network.
More information should come out today.
As for powering down / buying / selling, no-one knows for sure.
Here is the medium announcement post.
https://medium.com/@TronFoundation/steemit-joining-tron-ecosystem-6ad66584d0b