You think they have a plan?
Generally. From what we've seen in the past, the Cowboys tend to try to make sure every position is filled before the draft with a player who can start at the position. (Note that I said start, not be worthy of starting.)
Not saying that there plan right now is to play Pollard at slot receiver if they lose Wilson, but I think it could be a consideration in the thought process for how much they are willing to pay Wilson. However, their thought process could be try to retain Wilson and if not, replace him with whatever third receiver we can get cheapest.