He hit his ceiling here. Maybe he could do better somewhere else in the right circumstance, but 7 years of 9/10 wins is enough of a sample size to move on when your head coach is a constant embarrassment, and there's still plenty of on-field embarrassment.
Your examples don't work for your argument either. Mack Brown started the way Bo did, but he got better (11 win seasons, top 10 finishes, etc.), as well as playing the politics right and being a gentleman about it. I have no idea what you're talking about with Oklahoma, but Bob Stoops had that team at a NC caliber level from year 2 pretty much through year 17. Immediately, and sustained.
They're both adults. What kind of scenario are you imagining, 42 year old Frost calls up Osborne asking, "Do you think I should take the Nebraska job?", to which Osborne responds, "No definitely don't they're total losers that fired 9 win coaches"?
ANYWAYS
Every time these discussions come up it's equal parts humorous and sobering to see how out of touch with reality some of internet fanbase is. Kirby Smart isn't coming here unless he sh#ts the bed at Georgia. Dan Mullen isn't leaving MSU anytime soon barring something incredibly unlikely and unpredictable. Chris Petersen? Please, there's literally zero percent chance of that happening. DJ Durkin? B1G coaches have unspoken rules about leaving B1G schools for other B1G schools, and he also hasn't proved anything other than a losing season and beating a bad Texas team.
Scott Frost is and will continue to be our best gamble that we know of. If it's not him, the only hope is for it to be a Fuente/Herman/etc. before they were thought of as hot commodities.
