Ask Air Canada. They had CRJ200's. Lasted pretty long then dropped them in favor of the E175/E190. Then dropped the E175 to a cheaper regional.. Think the 190's are kind of the cut off point.. Its been tried before in the USA Midway airlines 737 and CRJ200's. USair has dabbled in it... Just not long term ideal for the Majors to invest millions of $$ in a 76 seat plane. I see a shift of majors spending money to "refleet" there widebodys..
Stability in it..