The public was surprised when Global Rallycross imploded last spring, but apparently the organizers weren't paying their bills or the event purses, and what I heard was that the big teams pulled out when the organizers announced the top level series would be run in spec cars rather than the sponsoring manufacturers cars.
There's an "American Rallycross Championship series emerging (https://www.arxrallycross.com/schedule/) but I don't know how viable it is.
I found a substantial number of the teams tonight on the Velocity Channel, running in the "Nitro Circus Rallycross" series (https://nitrocircus.com/the-kicker/featured-news/2018/06/19/nitro-world-games-2018-adds-rallycross-fmx-quarterpipe/) Including Travis Pastrana, Scott Speed, Steve Arpin, Mattias Ekstrom, Ken Block, and Tanner Faust.