I don't see any way Cal will end up back in the NBA, unless he wants to take a pay cut.
UK pays him loads of money, because he's worth it at the college level.
He's not nearly as valuable at the pro level, so he's unlikely to run into a pro team that's willing to pay him more than UK pays him or will pay him.
He's in a spot you didn't used to see before college sports got to be such HUGE business. He's a lot like Saban in that no pro team is going to match or exceed the pay he gets at the college level, because his most elite skill (player getting) is not something that's of equal or greater value to teams at the next level. Saban's great in the same way. Part of his greatness is his attention to detail and his system, but an even bigger part is his ability to stack the deck, so that his team has better players than 95% of his opponents. That carries a lot more value in the college ranks than in the pro ranks, where you can't stack the deck so heavily in your favor.