Performance is likely to be relatively predictable, slotting in between a 5500 XT and a 5700. It's probably going to be a little faster than the 1660 Ti, but might not be much more than 10% faster than a 1660 SUPER, which will almost certainly be priced lower.
Pricing is everything, and based on the underwhelming 5500 XT pricing, I'm fully expecting another yawnfest out of the 5600 XT. A 6GB version of the card might be "okay" at $250, provided they don't cripple it with an 8-lane PCIe connection or something, but I wouldn't be surprised if we saw higher pricing than that.
And really, it's hard to get excited about this card after the competition has reigned uncontested in this price range for the last year. Maybe if they had released these cards back in the summer near the launch of the 5700 and 5700 XT, but at this point the 1660 Ti has already been out for nearly a year, and even the 1660 SUPER has been out for a couple months. Plus, with consoles featuring raytracing hardware arriving in 2020, and support for it on the PC side of things gradually increasing as well, it brings into question how well any of these cards will hold up in the long term. A year from now, there might be mid-range cards with semi-decent raytracing support, with big titles universally supporting it, and all these cards might be relegated to running games at medium settings at 1080p.