I don't want to start Yet Another Remote Wayland argument. I've seen enough from the Wayland folks to convince me that remote display is possible.
But I do want to nip this whole "RDP" thing right in the bud. Remote desktops are NOT WHAT WE WANT (well I'm sure some do, but many don't). If you're used to Windows then you may think "remote display" means "remote desktop" but it is not the same thing at all. We want to have support for remote display on a _per application_ basis, and even a _per-window basis_ for the same application--and of course all its related display objects (menus, etc.) and where its events come from (keyboard, mouse, cut/paste buffers, etc.) should follow.
I have this today with X. The next generation of X, regardless of how amazing it is otherwise, won't be a realistic option for me until it has this support as well. RDP in Windows is much WORSE than remote X11, because it's functionally inferior. RDP can't meet the entry requirements, so who cares how much faster it is?