According to Wjm47196, AMD's next-gen Navi 10 graphics cards will be competitive with NVIDIA's GeForce RTX 2080. WJM47196 went on to say that they expect Navi 10 to be released sometime between Q2 and Q3, presumably of 2019. The forum post also pointed out that Navi 10 will have surprising power consumption, although we hope that's for the better given the low-power 7nm process tech employed.
This information needs to be taken with a bit of salt though; a truck load of salt actually. While ChipHell has been the source of plenty of cooperated leaked information over the years, we need to be temper our expectations. There is also no indication as to whether these Navi GPUs will have hardware support for real-time ray tracing like the GeForce RTX family.
AMD CEO Lisa Su recently claimed that Navi 10 will launch in 2019 and compete with NVIDIA's Turing GPUs, and it would make sense for AMD to target this level of performance for its next generation of graphics cards. We will have to wait for the GPUs to actually launch before we can say how they will perform in the real world though.
Rumors regarding unreleased AMD hardware have been swirling at a feverish pace in the past few weeks, especially regarding the company's upcoming Zen 2-based Ryzen 3000 Series of processors.