Iowa will have to win out - reg season and B1G tourney to pull a number one seed.
There are probably three teams locked into #1 seeds: Gonzaga, Baylor, Michigan. The other one is what is up for grabs. It will go to either Houston, one of Illinois or Iowa pending BTT results, Alabama, or possibly OSU in the right circumstance. I think most people in the country expect there to be 2 Big Ten #1 seeds, but the BTT could cannibalize that.
Houston has no shot left at any big wins to improve their resume, but that also likely means no more losses until selection Sunday. They've only played one ranked team that they beat. They may back into the 4th spot if they don't lose and Illinois and Iowa falter. But every other team has a better shot at improving their resume from here on out.
Illinois has two top 10 games left, plus whatever happens in the BTT. If they win both of those and get to the BTT title game, they are probably the 4th #1 seed, unless Iowa beats them in the BTT game. But the BTT bracket may not line up for that possibility to happen. Win out and they are easily the last 1 seed.
Iowa has a top 25 game left in Wisconsin, plus whatever happens in the BTT. If they win these last two and get to the BTT title game, they have a shot at the 4th #1 seed. It depends upon who they beat in the BTT and who they lose to. Beat a decent mid-pack team and Illinois then lose a close one to someone respected like Michigan or Purdue in the title game and I think we still have a good shot to jump Houston to get the #1. A 3 loss Houston could complain, but they haven't played even remotely as close of a schedule as ours considering Sunday will be our 12th game against a ranked opponent. Win out and we are likely the last 1 seed.
Alabama has played 4 ranked teams and lost 3 of those games. The SEC is pretty bad, so they only have a shot at beating Arkansas in the SEC tourney to improve their resume. I see them staying on the 2 line if they win out unless a the combo of Houston, Iowa, Illinois, and OSU all falter. Just not enough chances to improve like Illinois, Iowa, or OSU have.
The wildcard is if OSU pulls their game back together and wins out. That would be a win against Illinois, plus likely 2 wins against some combo of Purdue, Illinois, Iowa, or Michigan in the BTT. That would be enough to move them up to the last #1 seed. If they lose to Illinois on Saturday it would be 4 straight losses, 3 of which to current top 10 teams, and would likely put a cap for them on the 2 line.