If it breaks backward compat then why not allow the customer to choose that with a newer version of RDP. This way the user can choose to use either the old non-secure way or the new secure way. They understand what will happen if a machine loses sync access with the new way and for them it might be a better solution. This is far better than keeping a single method available to everyone that is insecure.
Also on my Windows 10 machine I can turn off the RDP service using Settings->System->Remote Desktop Access->Enable Remote Desktop->Off, which is obviously only a solution for machine that dont require RDP, but if you dont RDP to your own machine, then better to disable.