I am not so sure. If we can trade him and get something then maybe. Outside of that, I think McFadden still has a valuable role here. He is a good RB, good pass protector and good pass catcher. To me that puts him ahead of Dunbar who is only a pass catcher. Morris is meh in pass protection and as a pass catcher. Jackson is very limited as a runner, not much wiggle, pretty much straight line guy. I think we would have no problem getting Jackson onto the PS.
We already have several "key" ST guys that likely are going to make the roster simply because of their ST game. Heath, Wilber, Church, Gachkar, Hitchens are all good ST guys. We don't have to force a spot for a rookie RB.