So... With TCU's loss, what happens now? Is a rematch basically guaranteed?

The committee has said it wants to avoid rematches where possible. In this case, they can easily accomplish that. Both TCU and OSU are 1-loss teams that dropped their final game. But OSU got blown out at home -- by a team in the CFP, no less -- while TCU lost in OT in a conference title game. OSU's loss was worse on its face. Also, it wasn't in a title game. Also, TCU's strength of schedule is higher. So: OSU is 4 and TCU is 3. This also has the benefit of a) avoiding an immediate rematch, which nobody wants, b) setting up a potential title game rematch, which everyone would want and c) spaces out Michigan and Ohio State, which will both draw huge ratings in the semis (whereas Georgia-TCU would not). This is not a close call.

Tcu has 12 wins vs osu 11. 

Not a chance.....in the first round.