Yeah, NIL dramatically altered the landscape in a lot of ways. Some very positive in that former doormats like Vandy and also rans like Tech and ASU do have the capability to run with the blue clippers, to a degree. I think, broadly speaking, it's created more parity across a select group. I do think that group is bigger now for a chance to complete.
That said, on the down side the haves really have and back door deals that Saban and Alabama lived on just don't exist like they did prior. Mainly because you can stack talent 3 deeps who are college starters much less NFL caliber, particularly around the lines where Saban and Bama always dominated. Saban saw the writing on the wall and GTFO while he could.
I don't think hed come back because there's a very real chance, no matter where he went, for his legacy and mythos to be tarnished. Add to it, the additional strain and work required with PR and such for the HC, I dont think it would even interest him. A HC isn't or really shouldn't (imo) be an Xs and Os guy anymore. The consistent winners will, I firmly believe, end up being the OSU model. HC manages the program and "character" of the team, not what happens on game day. (Aside from ref shenanigans and bullshit - I'm looking at you Kirby)