A locally run, self hosted AI assistant that can do everything ChatGPT can do, where you have control and ownership of the model and can mix with open models that are updated automatically, - and a mechanism where it can be instructed to design widgets as well as other simple desktop features that adhere to system wide privacy and security policies on request...

...yes.

Proper HDR support and AMD to put in better HDMI 2.1 support on the open drivers.

The ability to easily resize scrollbars, KDE.

We had them right for so long.

Gnome mobile shell

Cinnamon has this but I wish KDE had it. The ability to right click an application in the task bar and have the option to "move to other monitor."

Desktop as a service. With the latest feature being worked where apps can be handed off to another compositor, I want the next stage where my compositor and desktop can be swapped with my intervention or notice. Wanna do redundancy? Running the backup live as a hot swap. Wanna do live updates with no interruption? Start the next compositor, try and loads the apps, if nothing breaks, swap the user, if the user doesn't hit the notification to revert kill the last session.

Add in better remote compositor support and it can get really cool. Allowing for a distributed DE across your devices. Making high availability more possible as well, but that might actually be overkill.

Desperately waiting for Gnome Nautilus to not suck major ass (type ahead search, faster performance... hell, just make it like Dolphin, pretty much).

Not a DE, but I'm really waiting for tearing on sway so I can play games without a second tty 🥲

GNOME desktop icons that aren't an extension that isn't as good as something native.

KDE's VRR and XWayland fractional scaling implementations are pretty dope. Wlroots pls

Sliding Tiling Window Management akin to PaperWM for Gnome.