I haven't paid a lot of attention to Rex's broadcasting, but I did hear him on Costello's podcast and he seems happy doing TV.
at different times this year rex has pined for the jets and giants HC positions on air, as well as stating he'd be a good DC for some teams that need defensive expertise (cowboys) and would come back if the money was right, but then he plays it off like a joke
i think he really enjoys TV, i think he does great on TV (best was him taking any shot at Baker that he could, justified lol) and i think he's having fun, but if the right offer/contract came along he'd go back to coaching.