Why? Jags went out of their way to get him, so they certainly aren;t going to fire him after only 1 year. Only thing that could happen is that Urban decides that the NFL is a size too big for him and that he wants to slink back to College.
Rebuilds, especially coming from a team that has been as bad as long as the Jags have been, takes time. I assume Urban will be around at least 3 years unless as mentioned he decides that the College game is more his speed.
Today was actually a pretty decent game for the Jags all things considered. They have absolutely no one that can make a play on defense. Give them another year of top picks in the Draft to adress defense and they might start looking like a team.