There's not as much reason to stick around if there's doubt you'll be offered the head coach gig.

I'd probably take another job just for the experience. You'll command a higher salary if you prove that you can be successful elsewhere. You'll still be a prime candidate for the Utah head coach position. Experience as an NFL coordinator would be a great carrot to dangle in front of recruits.

The only thing your value proposition loses is the continuity. It will take you a little longer to get up to speed with your players and recruits when you come back. If your replacement coordinator turns out to be awesome, you might find yourself in 2nd place.

Are NFL coordinator contacts ever longer than 1-year? It could be interesting to see if he insists on 1-year only to keep his options open for returning.