Hard to say -- I think it could mean less 1-dimensional wrestlers 20 years down the line -- but probably not. College wrestling will still be around, and isn't going to lose popularity. Many kids do it as a means of getting scholarships, and putting themselves thru school.
There are lots of collegiate wrestlers in the UFC, but not as many Olympic wrestlers make the jump to MMA. While I still consider wrestling a combat sport, it takes a different type of person willing to get in a cage with 4oz gloves on and get punched in the face (probably KOed a few times in their career) or choked out. Only a small fraction of wrestlers out there would be willing to take a MMA fight -- and they will do so with or without Olympic wrestling.
The wrestlers out there that are thinking about making the jump to MMA will just make the jump sooner I think, since Olympic competition is out of the picture.