I don't think availability will be poor. If you look at the current RX 6600 series, they are pretty much available all the time. The only problem is the price. And this being fab on TSMC 6nm is more advanced on paper as compared the 7nm used by the higher end chips. So I don't expect prices to get any better.My calculation give that 6500XT will have 1660Ti level of performance @1080P and marginally below Vega56. Only price and availability will make it or break it.
I feel on paper, it will perform around a 1660 Ti. However the GPU is VRAM limited if it only have 4GB, and performance will quickly tank at high image quality settings. And at least based on observation of past 4GB cards from both Nvidia and AMD, the performance for the latter tends to drop faster. The not so distant RX 5500 4GB vs the GTX 1650 is a good example.
I think pretty much any gaming capable GPU cost a lot now due to shortage and scalping at every level. Having said that, I feel that AMD's RX 6600 and lower GPUs are so gimped when it comes to specs, that they cannot perform well. This RX 6500 and 6400 is the ultimate gimp with meagre amount of cache, and narrow memory bus. While AMD can argue that the card will run games at a specific resolution and settings, but I suspect for unoptimised games, the performance will tank. And I really don't like to when AMD is artificially limiting overclocking and thus, limiting the potential of the graphic cards. If they want to give people reduced memory bus, at least have the decency to let people they and increase the memory bandwidth by overclocking the memory to its full or close to full potential.Why bother to make these cards that have 64bit bus lol. stop it please. and 4gb? sigh. There's plenty of cards you can buy on the market that's better. Even my WX 4100 is faster than that card.