If STOVL (or CTOL) JSF ends up being chosen for FCBA, then I suppose the USAF version of JSF could be FOAS. EF could be marinated into FCBA, for sure. But the capability of the ac would be massively compromised. As for EF doing FOAS (though not before 2018-ish), hmmmm. Although the EF airframe has had bits added to improve air-to-ground capability, its in no way designed to be a FOAS-type ac. Some people still talk about conformal tanks, (even Industry concept engineering folks) but the designers who would have do the work ruled out conformal tanks 10 years ago.