I smell Fail!
If your wifi can't handle it, it's unlikely your internet connection will.
Far more usefully, corporates could run their own mobile network and the carriers will lose telephone calls without business going to the hassle and shakiness of mobiles with sip+wifi.
The only benefit I can see would be if most traffic was not for the corporate LAN. Universities perhaps, where the university wants to reduce LAN traffic by getting the telco to charge for it and not providing it themselves.