It would take 10 years, minimum, to develop a domestic fight.  Likely more like 15.  And who has the tech/R&D base to realistically attempt such a feat ?  Why BBD/CAE/L3/Heroux etc., all of whom are involved in the Super Hornet proposal, except BBD, and are all in on CSeries.  Add to that the likely fact that no one else would buy it (hello Arrow) and the unit cost would be eye-watering.  Which was the real reason the Arrow was cancelled, much as though conspiracy buffs might object.  That was the unanimous recommendation of the service heads in 1958 and painful though it was, the right one.  The big error was agreeing to take the Voodoo and Bomarc when the McDonnell Phantom II was ready for service,