The 5700xt is not much slower than a 2080, maybe 15 percent. Do you really think AMD are bringing out a much bigger chip for only a 10-15 percent gain. Whatever AMD bring out it will smoke a 2080. They already released Vega 7 which matched a 2080. If they bring a chip between 400mm2 to 500mm2 it should easily match a 2080 ti and if on the bigger side easily beat it.
the problem is we know very little other than its rdna2 nothing about its actual size, yes its been named as big navi but how big that is the question, amd does like to try and talk up efficiency now (even though they are still playing catch up) over raw performance on gpu's again IF they can match or even beat a 2080ti great, but il keep saying it they are still a generation behind nvidia, it will be amd's first ray tracing cored release, for all we know rdna2 is just rdna with ray tracing added.
as for nvidia i really hope amd closing in on them will finally get these prices calmed down a bit, BUT if a stock 3070 can beat a 2080ti, big navi is yet again amd playing in the midfield (and yes a xx70 series card is still midfield no matter what prices nvidia has slapped on them of late) and nvidia's prices will keep up at their eye watering levels for a bit longer, il say it again i can see it being a couple of years before amd beat nvidia at the high end unless big navi is a huge jump in performance architecturally and not just the biggest gpu they could crank out size wise.
il keep saying it i really do hope amd surprise us but i just dont think they will this time.