I feel like they'll do a ten or twelve team league. Get rid of Vegas, obviously.
You get rid of Vegas, easily, as finding a venue for them on short notice is going to be an impossible feat, and Orlando absolutely stunk up the joint, making them a possible contender to be removed thanks to poor attendance. As for the USFL side, attendance is harder to gauge as teams play in pods, so most of them barely attract flies. Pittsburgh was really crap in the first year, but made the playoffs in year two where the whole North Division had losing records... but, man it's really hard to justify keeping them. And the New Jersey Generals are probably going to struggle in a very saturated New York market that doesn't bother mentioning the existence of a New Jersey, even by New Jerseyians.
You still have to move one of the Houston teams, of course, but I'd move them to Oklahoma or Nebraska. Luckily, the division alignment provides a nice east/west balance.
East: DC, Philadelphia, Michigan, Birmingham, Memphis, St. Louis
West: Seattle, Houston XFL, Houston USFL, Arlington, San Antonio, New Orleans