100% he leaves. He makes 600K a year.
Justin Wilcox preceded him at DC and got 16 million over 5 years to coach Cal.
Dave Aranda preceded Wilcox and he got 10 million over 4 years to be the defensive coordinator at LSU.
The question will be does he leave for another college job or for a defensive coaching position in the NFL.
If he goes to another college program as a head coach, just hope it's outside the Big 10. He grew up almost as close to Minneapolis as he did to Madison. Having him end up at Michigan, MSU, Minnesota, Illinois, or Iowa would be a disaster for UW in terms of competing for recruits.
I think it's just as likely he goes to the NFL. Look at some of the head coaches, defensive coordinators, and DBs coaches he played for. Dick Jauron, Rex Ryan, Chuck Pagano, and Jack Del Rio to name a few. Even more impressive, Mike Pettine liked him so much he brought Leonhard in to play for 3 different teams Pettine was either the HC or DC.
The only way he stays is if Chryst moves up to the NFL and Leonhard gets the head job and I don't see that happening.