I find the 5700 quite interesting, as normally, that's a low-mid-range card, naming-wise. x800 models tend to be the main card and x900 would be high end. That's assuming they've gone back to that naming pattern, at least.
The 5700 is shown as being 10% faster than a 2070 in the Strange Brigade demo, which puts it directly on par with the Vega 64, if not just slightly above it. This would make sense, if they're aiming for this to be their new baseline card. The question becomes where a 5800 will land. As you almost have to assume they'll be aiming for +10% on a 2080/Radeon VII.
If so, then the 5800 or equivalent might be rather impressive, if the price isn't stratospheric.
Furthermore, if it maintains a 10%, or close to advantage at 1440p and above (or at least just at 1440p), then the 5800 will be faster than the VII in a lot of games.
Also, going by their 1.5x per watt reference, I'd assume these cards will run around the 200watt mark, which is pretty impressive also and really all they need to do to be on par with competition. The fact that it is 7nm makes this pretty much expected and the overall increase in performance/decrease in power usage less impressive, but it is what it is.