The splash comes from something more than just mtb vs. road. Andi is also now organizing a race in Morocco, somewhat exotic but easily reachable location seems good, I think the route is fahionably gravel/allroad for a big part. But still no one talks about it. It hasn't been marketed much though, which kind of makes it look like a nice mysterious unorganized true grassroots event. Maybe too much so.
I'm expecting to see more adveturous ultraraces that include gravel/allroad/whatever. Or hoping. Though that has been the direction for the big events, TCR, NCT, the new Bike non-stop across the states. Looking at a map, it would seem simple to make a gravelroad alternative for the Indypac, there's one gravelroad going through half of the country along a railway etc.