The Sixth Generation Fighter is around

[su-47]

I think next gen fighters would be highly advanced UCAVs, flown by skilled operators from the ground. They will be stealthy, have supercruise and carry Ramjet BVRAAMs or maybe even laser weaponry. In performance they will outclass any fighter today. They will also carry radar cancellation, and might be swing-wing, like gambit mentioned.

They might also be possible of active reentry, whereby they can leave the earth's atmosphere and enter space, and then reenter the Earth's atmosphere at the desired location, effectively reaching any point in the world within minutes of take-off.

just my thoughts