re: Is there even a viable coach out there who could replace Saban?

There is no replacement

Lanning - He's about as good as any up and coming coach with a little HC time and good pedigree. And he might come in and retain a lot of what Saban built because he coached under Kirby and probably hasn't had time to really formulate what his program buildout looks like.

Dabo - Top 3-4 coach in CFB by any measure, and he'd come. He wouldn't crash the program and he might win titles. Bama fans don't want him, but it seems like a low risk, high upside option. I think it's highly unlikely someone comes in and wins multiple titles in the next few years at Bama, but if anyone could, it's presumably Dabo (Kirby isn't coming).

If you start with the assumption that someone is going to have a chance to win a title using what Saban built but that after that it's a crapshoot and you're probably going to do this again around 2030, it takes some pressure off.