With its planned 1763 F-35s, 187 F-22s and a notional 1900-aircraft force, the idea is that the F-35 does replace the F-15C and F-15E.
However, even at 80 jets per year, planned production continues until 2040 (2038 buy year). Since any major upgrade of the F-16 has been
canned for the foreseeable future, the F-15C/D/E will soldier on until then.
ORAC - This will require some extraordinary life extension, and I suspect Boeing plans to supplement that with new airplanes.