It depends on how much Jacobs wants. At age 29 he might be good for a 2-year contract. He didn't have a great season last year, not like he did in 2010.
Acquiring Jacobs would certainly mean letting go of Grant, and Clifton, and Walden, but we sort of expect that anyways. The question is still Wells. If we let him go we need a center. Can't rely on Dietrich-Smith. Zeitler as a draft pick is being thrown around. We'd have to get him in the 2nd round and might have to trade up, because by the end of the 2nd round he will probably be gone.
The question I have is whether Jacobs is the punishing power runner that could really help us. Some say he plays soft for his size.
If he can be that, then signing him for a reasonable contract, getting a top pass rusher like Perry or Branch in round 1 plus a trade up for Zeitler in round 2 could have the makings of a good off-season.