First of all, Jason Taylor is almost certainly going to be back and the weakside OLB. He's an ideal fit, Parcells suggested he wasnt going to get rid of him, and he was one of the guys Ireland contacted immediately.
Crowder can make himself a FA this offseason I believe, has frankly not been that good, and probably doesnt have the game preparation skills Parcells is going to want.
Porter pretty well showed this year that he wasnt a great fit for strongside OLB in general, and will probabaly considered less so this year given that Parcells and Co. prefer their strongside OLBs about 20 pounds heavier than Porter. It's possible that Porter ends up seeing a rotational role, or switches to ILB(Parcells defense has a long history of pass-rush oriented, formerly DE/OLBs at ILB)