1. Entirely free to switch: the enterprise customers will be where the money comes from
2. You get to keep all your files: Not too hard, actually. I bet a half dozen experienced coders could figure out all the edge cases in a month or two
3. You can go back any time: Also not too hard, just either store information needed to reconstruct their original filesystem on disk, or in the cloud
4. Faster: I'm sure Windows spends a lot of time doing things it really doesn't need to be doing. 50% is probably unreasonable but removing three decades of backward compatibility and tech debt can't hurt