TCU got cancelled solely because of Gary Patterson complaining that TCU has zero shot at making the playoffs if they have to play Ohio State. He was pissed when the TCU AD scheduled that home and home. So TCU backed out of the home and home by replacing it with 1 game in Jerry World to help recoup some of the lost money.
This isn't some rumor either. Gary Patterson literally came out last year and admitted he was the reason for cancelling the series. I believe his quote was something along the lines of 'It's bad for business' or 'It's a bad business plan' (to play Ohio State).
Ohio State replaced that game with Miami (Oh).