That tactic only works for as long as nothing breaks. So far the stuff Windows introduced for better security (ie. UAC) very rarely break things both by trying

That tactic only works for as long as nothing breaks. So far the stuff Windows introduced for better security (ie. UAC) very rarely break things both by trying to emulate the older behavior (ie. UAC tries to virtualize writes to Program Files older programs do) and by allowing you to bypass it and just let the program do what it wants (run as Admin, compatibility flags in registry/settings in shortcut, etc). Even when that isn't possible there are often workarounds to make things work. In general i'm very confident i can make any older program or game for Windows to run on modern Windows 10 - usually with minor tweaks. If Microsoft breaks this, i'm certain they'll completely misunderstand why people keep using Windows.