They never tried to kill anything outside the Microsoft store. That's just what Tim Sweeney and developers got fearful of and made a big fuss about (not saying it's not worth making a fuss about, but they never announced they would do it). Microsoft did introduce more limited versions of windows that had sideloading disabled by default, but these were low cost versions of windows generally aimed at children and grandparents / non tech people, not at their gamer user base.