Maybe more detail is needed.
If an SC6G (so-called sixth gen) fighter is to be produced in quantity for the USAF in parallel with the F-35, starting round 2030, the USAF will at that time be acquiring, each year, 80 F-35As, 8-10 LRSBs, xx SC6Gs, along with tankers and T-Xs. By the way, the replacement of the ALCM (LRSO) and Minuteman III (GBSD) will also be in full swing. I think that is called "fiscally challenging".
Also, for those who think SC6G is a replacement for F-15s: the planned replacement for the F-15 is the F-35. The USAF still nominally has a 1900-fighter goal, which nominally is covered by 1763 F-35s and 140-ish F-22s.
And if the SC6G is to follow the F-35 into production (well after 2035) it is ridiculously early in the game to be funding prototypes.
It may be worth remembering, too, that until the mid-2000s the F-35 was not expected to displace any of the 339 F-22s.
Last edited by LowObservable; 29th Jan 2015 at 14:40.