I doubt a lot of solid 4e fans will be switching to D&DN given that it is such a retro move. I quit 4e a few years ago because I never really enjoyed it much and went back to 3.5 (tried PF too and didn't enjoy that either). So I guess I won't be "leaving" 4e for D&DN technically. But I am planning to buy the books, at least the core rules, and try them out to see how much I like the game once it is released. I have been half-way paying attention to the play-test packets, but only ran one actual play-test session. If I end up liking the finished product, I may switch to D&DN, but the jury is still out on that. We really don't know what the final game is going to look like. Each play-test packet changes lots of stuff. They seem to be taking a "Google" approach by trying a dozen things in the hope that one or two works out and keeping only the stuff that gets positive feedback. I'm not sure that is going to make for a good game, but as I said the jury is still out. Mike Mearls seems to be at the helm for this (from what I can tell), and I don't tend to see eye-to-eye with him. However, I do like a lot of the ideas I see floating around in the play-tests. I am a bit disappointed in the martial healing stuff, but we'll see how it all works out in the end.