Desgining and building our own "homegrown" fighter is pretty much out of the question. Our best bet right now is too purchase a replacement aircraft. There have been mention in this thread about just keep the CF-18 maintained and upgraded and it'll still be a very good plane. Well...Israel just kept upgrading the M4 Sherman with better engines, and guns for many years (ie: M50 Super Sherman), but they even realised that the M4 had to be dumped for a new tank at some point.