If we extend Revis, we automatically save about 10+ million against the cap, since he's currently counting for 25 million dollars against the 2015 hit. I believe 5 million is hitting it no matter what, which is how I came to the "10 million" dollar savings. This is assuming that he has an approx. 10 million dollar cap hit for 2015, which I find reasonable.
I don't see why that money couldn't be used for an additional WR, especially considering the fact that they are going to carry some money over + see an expected 2015 cap increase across the board.
When all is said and done, they could have as much as 30-35+ million in cap room, understanding that they have some of their own important players to try and sign, just the same as any other team.