There is implicitly no reason why all the on board systems from an F35 could not be put on a 4.5 generation plane as I understand it, obviously it would help that the F35's integrated helmet could be demonstrated to work.
It was 2010 when Northrop explained that the EODAS/EOTC+AESA could partly or completely be used by other platforms besides the F35B.
They also stated that it was not out of the realm of possibilities that their systems could be in use in other fighters before the F35 reached IOC.