It's been mentioned before, about MX being in a 'future Golarion'.
http://paizo.com/threads/rzs2nj5w?XCrawl-campaign-in-Golarions-future
Now that "Pathfinder Future" will be available this year as Starfinder, it's not an 'IF' but a 'WHEN' someone wants to figure out how to do a mashup.
Xcrawl has its own version of Earth. If we squint really hard we might be able to pretend that the Xcrawl-Earth is the same version that shows up in the older Adventure Paths that visit Earth.
If there is ever contact between worlds again, the Xcrawl sport/LARP and its tabletop Dungeon Battle RPG will eventually get exported to the Pact Worlds.