I've seen a few comments from people that said it looks like things are going backwards in the GPU market. On the plus side, power consumption is down. Otherwise - this makes for rather depressing reading I think...
https://www.pcgamer.com/uk/amd-rx-6500-xt-worse-than-rx-480/
you are not miles off tbh. the RX580 probably performs on par with this card or may well trump it. tho this card is DX12 where older gen cards really struggles. so be interested in seeing their performances in DX11 firestrike for instance benchmark.
but what you do get in the latest chip is efficiency. that isnt really much a win for gamers...messed up market and greedy, manufacturers