In Bentonville, Arkansas, there are a number of high use MTB trails that are being paved over as a permanent solution to erosion, Trail Poaching, etc. (see link to video below)
Paving over existing trails along with fast riding on existing shared use trails is given rise to a new discipline of Velo Sport which I've coined as XCP (P=Paved)
XCP is actually not a novel concept when you consider how modern XCO courses like France's Olympic XCO course incorporated a number of paved and 4 bike wide graded gravel sections in it's layout.
One could argue that with the exception of the man-made rock gardens, today's XCO courses are far removed from the rugged 50K West Virginia back country courses we raced upon in the late 1980s.
Check out this video titled Asphalt Trails? Why these MTB trails are absolutely genius:
Retro out.