Hm, so what about R9 380? That's mid range card. Almost 2X 7770.
2017 is real close to typical new gen, what's the point? This year is better for stop gap upgrade.
It'd be higher than a 7770. The XB1 was around a 7770 because a huge chunk of the space on the APU that was GPU for the PS4 was used for eSRAM for the XB1. eSRAM Compromise for memory bandwidth. The DDR3 in the XB1 has much less bandwidth than the GDDR5. Graphics stuff eats bandwidth up. So they had the eSRAM help cache the difference.
PS4 and XB1 have very similar designs and basically sony lucky-out on GDDR5 prices and MS deciding Kinect was the future is most of what the performance difference is.