I hope that XFCE remains a solid lightweight desktop option. I've become a huge fan of KDE over the past couple of years, but it certainly isn't what you would consider lightweight or minimal. Personally, I'm a big proponent of Wayland and not big Rust detractor, so I don't see any problem with this. I do, however, wonder how many long-time XFCE fans and the folks who donated the money funding this will feel about it…
Very long time (since 2007) XFCE user here. I don't think this is accurate. We want things to "just work" and not change for no good reason. Literally no user cares what language a project is implemented in, unless they are bored and enjoy arguing about random junk on some web forum. Wayland has the momentum behind it, and while there will be some justified grumbling because change is always annoying, the transition will happen and will be fairly painless as native support for it continues to grow. The X11 diehards will go the way of the SysV-init diehards; some weird minority that likes to scream about the good old days on web forums but really no one cares about.
There are good reasons to switch to Wayland, and I trust the XFCE team to handle the transition well. Great news from the XFCE team here, I'm excited for them to pull this off.