This is excellent news. It's amazing to see the driver situation of Linux progressing so quickly these days.
"Progressing so quickly" just isn't the first thing I think of when hearing about difficulties like those described in that email.
Back when Matrox released their G200 card they used a little known fact in X11 that allowed them to do platform independent drivers. I'm not sure how it worked, but remember downloading the and using the "Linux" driver on OpenBSD to gain stuff like dual-head support. I'm not sure the same would work for hardware accelerated graphics, but it would be nice if Nvidia help getting their hardware supported on whatever platform people choose to use.
It does, however, mean you can port the Gallium version of the Intel Driver, or the Nouveau / Radeon free drivers, or the other Gallium drivers like Freedreno to any platform with just that one API switch.
I figure it was one of the justifications in funding Gallium from the AMD boardroom perspective - it isn't just a Linux driver, it is a pivot to easily get their driver on any other platform they need it on, whereas Catalyst proves to be very specific, requiring developers on both sides actively maintaining it to have a Linux + Windows version, plus the OSX one they certainly have.
I believe Mesa does not even support EGL on BSD. Now I know the Nvidia driver doesn't use Mesa, but this indicates how little effort is being put into Wayland on BSD.
I can't say I blame them. BSD is primarily used on servers with no GUI, so the BSD community uses their limited resources to support that use case. It's the same reason BSD has poor support for WiFi and suspend/resume. But I don't think we're going to see Wayland on BSD for a very long time.