I'll buy in, that's for sure. And probably change it as my main DnD edition, at least for the first year after it's release. It was my experience with 4E, I doubt it'll be different, at least at first.
The real test, for me, will come about 6 to 12 months in, when I will either become bored by the system, or stick with it. I know myself as having a notoriously short attention span. If this game can keep my focus better than 4E did (for about 8 months), it may just replace the host few retro-clones I use as my go-to systems for fantasy.