I said this in the Storm thread along time ago but it bears repeating: it's all about exposure outside of the X-universe. Have these characters appear in comics outside of X-titles, have them interact with other non-mutant heroes and face non-mutant villains. Have them connected to other people besides mutants, add some mystery to their background.
In other words overexpose the hell out of them inside and outside the X-verse. Why can't Frenzy be an Avenger(Sunspot, Sam, Wolverine, Rogue)? Why couldn't Celia Reyes be on Strikeforce? Tempo couldn't join the Future Foundation?
Stop limiting the opportunities for these characters and stop thinking that they can only be in books about mutants and dealing with mutant issues.