Difficult to say. That kicks off a whole train of alternate history that is impossible to untangle.

It could have been developed into a tourism hotspot akin to Hawai'i or Florida. Or it could have been exploited and led to worse treatment of the Mayan natives than they suffered under the Mexicans. It might have been subjected to the same cartel woes as the region is now. Or it could have been sold or led to another independence movement / civil war.

Who knows? It is fun to think about though.