Y’know, you make a very compelling argument; however, if there is one movie that doesn’t need a sequel it’s “Con Air.” Seriously, it is the perfect stand alone movie. 
I remember seeing this as a kid and then watching it again as an adult. It is uproariously hilarious, especially with all of the dated 1990’s humor and action (lol). 1997 was like the summer of Nick Cage. How he went from “Con Air” and “Face Off” to “Left Behind” is beyond me.