The progression of Mitchell Trubisky is so incredibly important to this franchise and to Ryan Pace's own personal future, that I can't see him not hiring an offensive guy as head coach.
Pace knows that BAR-NONE, Trubisky MUST work out. If you don't hire an offensive guy, you're leaving it up to chance that guy hiring the right guy for OC, and that OC not bolting for his own head coaching job if he starts to get success.
If you have an offensive head coach and your OC bolts after success, it's less of a problem. If you have a defensive or ST head coach and your OC bolts after a year or two of success, that's a HUGE problem because he takes the whole offensive system with him and you have to start over with someone new. I can't see Pace taking that chance---His success is tied too much to Trubisky to take that chance.