The reason I thought they'd go with 3 RBs is because this is going to be a pass heavy team (our Oline is better at pass blocking than run blocking), we have an incredible corp of WRs, our RBs won't be featured in a pound and ground way, we have a really good accurate pocket passing QB, neither Kelly nor Davis have done anything to distinguish themselves, RBs are a dime a dozen these days, and we could use that roster spot to keep somebody who showed greater potential at their position than Kelly/Davis did at RB.
They'll pick up another team's cast off RB for the PS..... maybe sign Kelly or Davis to the PS, but I doubt it. They've been around long enough that if they couldn't break through by now, they're not going to.