A model of the F-15 was built, tested then dumped called the F-15SE (Silent Eagle.) It basically did what artik suggested, which was take the basic F-15 frame, strip it down to the bones and rebuild it with ultra modern avionics, etc and then handle some surfaces with radar absorbent design/material. It seemed to do much of what artik suggested, at a much smaller cost than the F-22. It was dumped. From a political point of view the SE variant has less umph than the F-22.
If the F-35 is all avionics there is no reason those could not be built into another bird. The F-35 is a platform, what they are describing is the data bus, link and system.
boo