well, it seems Konami thought Castlevania needed a new main villain, at least for the Lords of Shadow sub-franchise. Satan makes a decent enough main villain for me, as does the Forgotten One. I haven't beaten the Forgotten One yet, so I don't know how much of a main villain he is, but since Satan's coming back, I'll assume Satan is the main villain.
and even in the mainline canon of the story, Judgment hinted that Dracula's rise might have served some higher purpose, to thwart some kind of yet to be announced threat (perhaps Galamoth), so it seems to be headed in that direction in both timelines.
which is just fine to me, though there's nothing quite as classic as a good ole Drac is the ultimate badguy story that we need to be concerned about.
i'm currently reading a parody fanfiction Modern Problems which seems to have Walter Bernhardt be the main villain. I wouldn't mind seeing him make a come back either.