I think the Tilt Rotor is going to be the domain of the Rotary Wing pilot. The fixed wing guys are going to look at it and see a Turbo Prop aeroplane and though it may be fast for a Heli it ain't a jet.
I think the Helicopter is in no danger of being replaced in the near future as the Tilt Rotor is very expensive, small and un-proven.
There will be markets that may open up because of the Tilt Rotor i.e.off-shore oil fields that are beyond the range of the current Rotorcraft fleet.
Airports require a lot of land and eventually as real estate becomes a premium as in the North East U.S.A , Japan, Europe they may find a niche as a regional feeder if they can be built to carry 30+ passengers.
I guess time will judge.