El Mariachi III is coming out or Desporadoes 2 if you would. Anyways since Once Upon a Time in Mexico coming out what would hope to see.
Probable:
-See the guy from the beginning appear again
-More talk from the other two mariachis
-See a guy gets his head blown off by a handcannon
-The knife guy colmes back
Less probable
-Antonio Benderas talks smarter
-Bullet time moves
-Short bar tender comes back
-Like in all Rodriegez films more characters make guest star appearances from his previous movies
-Talk of making From Dusk Till Dawn 4