I don't believe for a second that anybody that interested in the first place won't end up buying it anyway, providing it turns out to be good.
But I've always maintained that publishers announce their games way too early. In this case, waaaaaaay too early.
Still don't think it'll make the slightest difference to sales, though. A big press conference, an onslaught of screenshots, a few trailers, and some playable previews will go a long way to reviving anyone's flagging interest. And if not that, an actual game that turns out well will seal the deal.
