I'd suspect AMD hasn't ordered Polaris wafers in a while and most of what is still on the market are leftovers trickling down. The RX570/580 won't be competing with the RX5500 once Polaris models go out of stock.Nice. The Rx5500 would be a failure if it failed to beat Rx 570, considering the latter's low price.
If the XT is only marginally faster than the non-XT which is itself often a fair bit slower than the RX580 and 1650S, then I'd expect AMD to have a hard time asking much over $160 for it. Still ~$50 more for AMD and its partners to split than RX580 assuming the 158sqmm 7nm Navi dies cost about the same to manufacture as the 232sqmm 14nm Polaris ones do.Supposedly, the 5500XT will launch on December 12. Let's hope it is less than $180!
Source: https://www.tomshardware.com/reviews/nvidia-gtx_1650-super-turingMemory capacity remains the same at 4GB, which today can be a concern for some titles running ultra settings. Running out of VRAM can significantly affect performance, so users will have to be careful with memory-heavy games, especially as time goes on and VRAM requirements increase.
Source: https://www.gamersnexus.net/guides/2503-amd-rx-480-4gb-vs-8gb-benchmark-is-it-worth-itAs for whether or not 8GB is worth it, it really depends. If you're playing games like Black Ops, Mirror's Edge with higher quality settings, or Asssassin's Creed and similar games, it is absolutely better to get the 8GB card. Deltas nearing 30% make a big difference to perceived fluidity of framerate.
But that's not all games. A lot of the games we tested show no perceptible difference, despite having measurable differences. They might be different by a few FPS, but not much more than that. Ashes of Singularity, Talos Principle, Metro: Last Light, and Shadow of Mordor saw minimal impact from the VRAM capacity change. Black Ops, Mirror's Edge, and Assassin's Creed had big differences that would actually be relevant. The Division was mixed.