What is out there that is new and fuel efficient enough to replace the current generation of planes and stay within current scope clauses?

Nothing readily apparent jumps out at me.

C series to big and a paper plane.

ARJ, Sukhoi? are within the scope clauses and are actually flying. I guess I don't see a Russian or Chinese aircraft being really reliable.

MRJ is a paper plane still

Maybe they go Q400 or whatever the next gen turbo prop is called.