It would be nice if there was a native support for dynamic rescaling of the remote desktop in accordance with the size of the Remote Desktop Client app (window), like it is done in Citrix solutions. Imagine a situation when you have multiple screens with different resolutions and you launch the client on one of those and move the window to another screen. Currently a reconnect may be needed in order to make the remote desktop smaller/larger to align to the new screen
Nathan Novak commented
Interestingly enough this IS supported already if you're using the Hyper-V manager to "RDP" to a VM instance.
This is extremely needed IMO. There is already support for this in Windows 10. For all other OSs, just zoom since viewing anything other than Win 10 on a High DPI screen makes RDP useless since things are too small.