It's hard to envision a program with more sustained success than what Bama's done the last five years. But I agree that Texas is a "better" job on most fronts.
I'm not sure I understand, though, how Saban going to Texas would trigger college football armageddon. Beyond them going back to winning the Big 12 and playing for titles, what are the larger ramifications? They already run their conference and get their pick of high school kids from the biggest football state in the land.
Consider his situation at Alabama, with constant top recruiting, insane facilities, huge assistant payrolls, large staff, and total mental control over most of the state. Alabama is and rightfully should be the favorite in every game they play for the foreseeable future (until something changes).
Now, take that same situation and make the in-state recruiting more than 3 times better (based on NFL players produced per state), and make the school far more attractive to out-of-state recruits (far better academics but you still don't have to go to class, much nicer surroundings, etc). Make the facilities even better (if that's possible). Make the assistant coach salary pool literally a blank check. Make the non-coaching staff even bigger if he wants it.
Texas would give Saban an identical situation to what he had at Alabama, but his resources in terms of money and recruiting would be vastly improved (a terrifying thought). What recruit in the southeast wouldn't want to go play for Saban? He knows SEC country like the back of his hand, those relationships aren't vanishing, and Texas isn't cold, the girls are just as hot, and you play in just as many marquee games. The only guys he'd miss out on would be those who were really attached to a specific school, not the kind of guy who wants an "SEC atmosphere" or whatever. Between those connections, the Texas brand, and the Nick Saban brand, there's a realistic potential he could put together a class with unprecedented amounts of 5* recruits - approaching 10 in a great year wouldn't be out of there picture. The ESPN slobber would get even worse over Texas than it currently is for Bama because this move would probably make the longhorn network at least close to profitable. Basically, the potential is there for Saban to develop the most dominant teams in the history of CFB if he goes to Texas because he'd have the best of everything in the country except for Oregon's uniforms and Standford/ND/Duke/Northwestern nerd academics.