Will TikTok be sold by September?

It's highly unlikely, only 16.75% of TikTok traffic is from the US and Trump is trying to force them to sell based on this small market share or be banned again, instead you'll probably find all US traffic simply goes dark and the ban goes live again.

It's a bit like owning a shop and 16.75% of the people who use your shop live in a cult house that tells you you have to sell your shop to cult members by a certain date or they will stop their cult members coming in, it's much easier just to ban all cult members on and after that date than be forced to sell a very profitable shop to the cult.