I wouldn't blame the new people. You can't possibly keep up with a huge code base as Windows when you can't implement anything smart as it can always break something somewhere. You need huge tests just to change a small thing.

It would give them a better return to just make a new OS from scratch while keep supporting Windows for the next 10 years (maybe 20 for extended support) and let it slowly fade.

Or better yet, take the Edge route and use Linux underneath and change the appearance to MS' taste, have binary compatibility layer and call it Windows.