The reverse would be wiser: put the login session on Wayland after the Wayland session is stable: if there are bugs in the Wayland session the users could easily use other sessions.. But Fedora devs aren't especially known for caring about the users' pain, remember KDE4.0?

The Wayland session is already available. It just lacks features. That's why the next step is the login manager. Though from reading the latest discussion on fedora-devel, there might be a few complications to correctly automatically fall back to X.

> It just lacks features.

Does it work on NVidia closed source driver? I thought that this wasn't the case yet..

I only learned this recently: Red Hat is working with NVidia, only expected to work around Fedora 23 release. I've switched quite a while ago to the nouveau driver. Next machine will probably have an Intel. I'm waiting for something which is quiet, doesn't use too much power and can drive an Ultra HD monitor at 60fps without any hacks (seems to require HDMI 2.0).