The main protocol should be well outside patent protection, but some of the extensions (RemoteFX, audio support, etc) may still be covered, would have to double-check. Likely fine.
I would like to see something as capable make its way into Linux and Mac that's as ubiquitous. RDP tends to work better than the VNC options most other solutions are using under the hood.
Gnome and KDE both support RDP in recent releases. Works ok, but connecting is not as seamless as Windows, at least with mstsc.exe. I’ve found it somewhat buggy too (blank or black screens until rebooted for example.)
One of the big things holding me back was good Remote Desktop experience on Linux. Using Gnome RDP has been good enough for basic use for me.
How about spice? I don't know anything about the technical details, but it seems to offer most of the advanced features like usb redirect and I think currently gets video support. It's currently really only used in qemu but I don't see a reason why you can't use it as a general open rdp alternative.
I don't think the Free Software ecosystem should touch RDP. It only fuels Microsoft even more.
If Microsoft was the company they pretend to be, they would Open Source (Apache) DOS 6.22, FAT/ExFAT, RDP and they would allow for side loading of applications on Xbox.
