I agree with this. Unless you know for a fact you have your guy lined up, maybe even signed, it's a big risk to get rid of a coach. Just look around the SEC at teams who have hired short lived coaches. I am not 100% on this but wasn't MSST's coach there for 1 year? AU got rid of 1 about 1 and a half season in. Even a successful coach from somewhere else might not have the success expected when jumping in the SEC.
You're right about jumping to the SEC and I'll even say the BIGPAC now as that conference is loaded with top programs and coaching. I hate to say it, but some of the best most entertaining football will be the new match ups coming from that merger. USC, Oregon, Wash, UCLA, Penn, Mich, OSU. They may even win the ratings battle thanks to the PNW and Coastal markets. But I digress, market demographics/ratings are another discussion for another thread and time.
If you are a coach who's hot to trot, making a name, rising up some call lists, you're probably seriously looking at B12, ACC. Money and resources are just as good. Exposure via endless sports TV/streaming/media is good, road to play offs easier, not quite the overall pressure cooker.
Go to the SEC or BIGPAC...get fired or just get lost down the depth chart of talented programs and coaches or go to one of the other conferences, make just as much money, have just as many resources, as much exposure, and sniff playoffs?
That's why it'll be hard to hire. The up and commers in the ACC and B12 that SEC and B10 could poach at will in eras past...they're going to stay put.