If Texas, Rio Grande and the Yucatan Rebellions united in some kind of compromise, could this allow this new republic to survive to modern day? I'm thinking that these rebellions might be able to hold off a reconquista if they enter into a military alliance at least. Maybe they create a new nation modeled after the US. This new "Texian Union" could eventually become a southern rival to the US.
I don't know if this is even possible but its a interesting senario to explore.