I don't think it unreasonable that Spencer make it through at least 3 more years at a high level. He has no major injuries for his entire career and is more than physically matched to his position. Add in a good rotation for once and he is solid gold.
Retain he and Brent and the D/line is pretty much set.
SAM: Albright/Spencer/Wilber
SDE: Spencer/Crawford/Hatcher
Shade: Ratliff/Brent
3T: Hatcher, Ratliff, Crawford
WDE: Ware, Spencer, Wilber
Would like another SAM or a bigger tackle but you could go to war with that