Cox has confirmed that he and MercurySteam have moved on to another Konami franchise. I'm pretty sure the project was greenlit before LoS2 saw release, but don't quote me on that. It's highly likely to be Contra, given Cox's mentioning that it is the series that he would like to work on next.
As for Castlevania, I remember Bergeron saying that the next project was in the hands of Konami Japan, and that they expressed interest in doing another game within the Lords of Shadow universe. Whether that comes to fruition, or whether that means that the next game will be internal or outsourced are other things entirely. I'd be fine with getting some more Lords of Shadow Belmont stories, since there's plenty of room for them and I don't think the main trilogy exploited that potential enough. With IGAs departure, I doubt the old canon is coming back, as he was it's main architect, or that the new timeline is going away within the next game or so. I venture that we'll either get a new reboot, which may come off as gratuitous depending on how they do it, or they'll stick with LoS to present some series consistency for the new fans.
Or they'll drop it entirely, but Torashiro (a Konami insider from Neogaf) said that, in his eyes, Castlevania is doing better rather than worse, so I don't think that'll be the case.