Konami's E3 presentation goes live on Wednesday, so we'll know by then I guess.
It really wouldn't surprise me if it did end up a 'Vania, but I doubt that Konami would greenlight two next gen games in the franchise for development at the same time. They've typically remanded the whole bloody affair to cheaper development on handhelds thus far.
If it is real I have mixed feelings on it. I'd like to see new blood tackle the series, but I question if Kojima could capture anything approaching the 'feel' of Castlevania. It could be a great game in its own right, but if it doesn't feel right, it could run the risk of being a CINO (Castlevania In Name Only).