I hope they don't either but I suspect what they will do over time is introduce the Microsoft Store as the only way to install apps and programs in future. Which is in effect, a walled garden. They could argue that as Apple and Android do the same thing on their platforms, they should be allowed to do the same for "safety". Like with UEFI and Secure Boot on PC and custom ROMs on Android, they'll probably allow a way around it to reflect any anti-competition complaints but they will also make it both difficult and remove functionality for those who want to install programs from outside the store (such as what happens when Secure Boot is disabled).

Either way, Linux, BSD and other non-proprietary operating systems will still permit you the right to install whatever you like, even if they don't have the ability to defend themselves from any future legal action from the Big N. And at least with Proton, running games which don't rely exclusively on Windows is getting easier via Steam as time goes on, even if it isn't perfect at this time.