Strategypage covers the issue rather well here:
Dogfighting isn't quite dead yet and it probably never will be. But more and more, victory goes to the side that can reach out BVR and touch the enemy first with an AMRAAM. The F-35 was optimized for BVR combat because that has been the future of air-to-air warfare for some time now.
I just worry that we base our predictions on the future --which we assume has arrived--of air-to-air combat on very little data because we just haven't faced a major threat to wrest control of the air from us since World War II.
But I'm a ground guy, so I admit my basis of worry is based on the past and not the ability to model the future.