None of those boards were designed for gen4. Given that the more expensive boards are trying to do more things at the same time it's not surprising they might have issues.

Also note that no GPU will need gen4 anyway and won't for the life of these boards. The only devices that might use the extra speed would be PCIE SSDs. Even then you're unlikely to notice the difference.

At least Crosshair has 4.0 for M. 2 which can be used right now. No graphics cards has the need for better than 3.0 x16 right now, not even 2080Ti. Even 3.0 x8 won't bottleneck a 1080Ti.

Anandtech story seems to say this will go.

https://www.anandtech.com/show/14639/no-amd-still-isnt-enabling-pcie-4-on-300400-series-boards

Currently C7H is on AGESA ComboPi-AM4 1.0.0.2, probably when updated feature will go. I know where some of the Gigabyte boards had newer AGESA than what ASUS boards for this context are on, feature went.

AMD did make some kind of statement about it and that it would be disabled in the future. However, we already know that NVMe drives work well in the pcie 4 slot on the CH7.

Partly they're (probably) doing this because it's tech support nightmare. It just won't work on some boards. I've read some of the pcie tech docs which state that under certain circumstances, ver 4.0 could run on 3.0 hardware, but with some limitations, most notable distance from cpu and signal paths that don't receive to much interference.

So if it gets disabled, I think the main reason will be to sell x570, then to prevent too many tech support requests.

Now we know it works on our board, I think they would be idiots to remove the functionality from us. We need to tell them this!