Seeing how we have talked about what CV has lacked preventing it from being mainstream, how about discussing what could make it mainstream?
I'm no game developer, but I do have an idea for a new CV game separate from all the others. Basically, you play as Dracula trying to reclaim his castle which has been taken over by a new species of vampire who aren't hurt by the sun. They only sparkle and are so emo.
As far as gameplay would go, you have your chose between two versions of Dracula: Classic Mage like in the early games where he would teleport/fireball routine; Warrior like Gabula in LoS2. Just imagine tearing through "team Edward" as either version of Dracula and reclaiming the castle from those freaking sparkling beings who give vampires a bad name. For someone like me who hates twilight and feels that it ruined vampires, I think it would be a lot of fun regardless of if it had a strong story or not.
A Castlevania game where you play as Dracula, for me, feels like a Smash Bros game where Ridley has been made playable through rescaling his sprite and nerfing his powers. I simply can't feel it. It happened with LoS2. I can't see Gabriel as Dracula. I simply can't. He'll always be Gabriel. Dracula doesn't exude warrior-esque feels, and thus I can't see him walking, running, attacking melee, flinching. I dunno, doesn't feel right.
As you proposed, here I go.
How to make Castlevania mainstream:
-Make the protagonist mute and characterless. Let the player sympathize with the character. Make it's gender and class selectable, too. Male or Female, Vampire Hunter (Whip), Warrior (Swords/Flails), Mage (Magic). Yeah, make it like "The Arcade".
-Make it disconnected from the main timeline. People won't play Castlevania because of the sheer size of the franchise. It scares people. See how LoS fared? That's because it felt so much disconnected that people received it as being a completelly new game. It
felt new. (However, new doesn't mean good).
-Add Alucard somewhere.
-Advertise the game as a [movietrailerannouncervoice]"New epic take on the classic gothic tale of Dracula!", "Explore a vast universe ravaged by darkness!", "Face hellish creatures in relentless combat!", "Customize your hero with relics and weapons to crush your foes!"[/movietrailerannouncervoice]. Yeah, advertise it like a MMO;
-Add tutorials in between loading screens. Bitches love tutorials in between loading screens.
-Make the story have as much relationship with real world events as possible, and incorporate in it actual events as much as possible.
-Make Dracula witty, snarky, but evil to the core. Make people love to hate him.
I think that's all.