The Simon article comments broached this topic so I thought it would be a neat and quick answer to give. Lets all agree on one thing,
WE WANT URBAN FOR AS LONG AS HE'LL STAY. These replys are going to be all opinion based, so no bashing, no one is a homer for saying he's a lifer, no one is a troll for saying he is gone in 3 years.
I believe that him staying will be very dependent upon his coaching staff, and if we see a mass exodus of assistants. I think it is safe to assume Coombs and Hinton are going to be around. Warriner, Withers, and Fickell all have head coaching aspirations and I think will be here shorter than longer. Herman is a young up and comer who may be around for a 3-5 but I think will ultimately get a chance to shine on his own and take the bait to. Bro Vrabel is probably solidly here but may follow Bro Fickell to his new HC destination.
In short, if he is able to keep his trusted staff in tact, I could see Urban staying around for a long time. I believe the biggest cog in how long Urban stays around is truly Fickell. So with Fickell staying, I think we could see Urban for 10-12 seasons.
Without Fickell and with a constantly changing coaching staff, I think the more realistic time frame is 6-8 seasons. 6-8 wonderful and magnificent seasons.
What do you guys all think?
EDIT: @HODGE, I don't think he will ever leave for another college position, and I highly doubt he leaves for the pros. When he leaves, he will be retiring from coaching IMO