User blog comment:X-Men Are Cool/Next Year's Crossover/@comment-3127448-20171130072227

The next crossover should be on Supergirl's earth. Mostly because Diggle can react to all other known aliens. Cat Grant can meet them all and fawn over all of them (she needs to appear too though).

It gets boring having all the crossovers in Central City. According to the Flash S3 Comic Con, most of the actors want to crossover to Supergirl's earth.