I wouldn't be so sure.
It seems many want TO to take the AD job at least on an interm basis, say 18 months. If that is the case I do not see him firing Callahan. Pushing for Cosgrove and others to go maybe, but not Callahan. TO would not fire and then hire a new coach knowing a new AD would be coming in within a year or so.
If TO takes the job either on an interm or permanent basis I feel he'll give Callahan this year and maybe next year with some staff changes.
It was SP that kept TO out of the mix not Callahan. With SP gone TO and CAllahan may get along well, who knows.
Sometimes we have to be careful what we ask for, we just might get it.