Plasma 6 still installs the X11 session. This change will make it so the Gnome X11 session is not getting installed by deafult, so you need to install it yourself if you need it. In Plasma 6, you just change to the X11 session in your Display Manager.
No, it is not the same thing. From the Pagure issue:
From my recollection the WG earlier discussed about the removal of gnome-session-xsession,
but we decided not to do that (wisely) until upstream drops it
It’s not like KDE, and when someone updates to F40, it won’t even remove Xorg. It just won’t be installed by anaconda by default in new installs.
Your quote describes literally the exact same thing that Fedora KDE 40 does. Yes, they wanted to go further and remove the Xorg bits already, but that got rolled back.
The KDE packaging team is no longer packaging Xorg, but the GNOME team is. The “re-upstreaming” is a completely different effort with no guarantees on bugs. In addition, the package providing Xorg support in KDE is to be marked obsoleted and will be removed when upgrading. Here’s the actual ruling:
KDE packages which reintroduce support for X11 are allowed in the main Fedora repositories, however they may not be included by default on any release-blocking deliverable (ISO, image, etc.). The KDE SIG should provide a notice before major changes, but is not responsible for ensuring that these packages adapt.
GNOME Xorg still has full support from the team that has always worked on GNOME, unlike Plasma’s Xorg on Fedora 40.
Because Gnome defaulted to Wayland for a long time, before they now plan to ditch it's X11 session, while Plasma just recently started defaulting to Wayland. I think Fedora 38 is when they defaulted to wayland in the Plasma edition. Gnome had a way longer lead time, IIRC.