Generating a lot of discussion in multiple places, and especially on Facebook, et al, about boycotting tourism in Colorado, California, etc., because of their anti-gun stances may have a telling effect. You can always ski in Utah, kids to Disney in gun friendly Florida, etc. Economics are precarious enough everywhere these days that I suspect that a decent amount of smoke in this line of thought will be enough to provoke some real discussion in the states looking at some sort of tourist boycott.
Colorado is probably the most liable to break on this, though, given that California can probably always rely on drawing people to its unique venues, same for NYC, but Colorado doesn't bring much to the table that you can't get in UT, MT, or WY, in terms of tourist experience.