Thernz already pointed out that Bram Stoker's Dracula had a very loose connection to Vlad the Impaler. As in, they were both Romanian. That was about it.
http://en.wikipedia.org/wiki/Vlad_the_Impaler I mean if you were going to have a historically accurate Vlad, Renonsgoods, you're not going to have Castlevania. You're going to have an Ottoman Wars simulator. The entire deal with Vlad and blood was just the myth that he soaked his bread in the blood of his impaled enemies to gloat at them. Besides the myth, Vlad was just an Orthodox Christian prince battling against Mehmed II's attempts to expand the Ottoman Empire deeper into Eastern Europe.
I mean that'd be cool, if this was the Total War series.
How do you gain access to immense, demonic power? Beyond living the bloody life of a warrior in medieval times, there wasn't anything really demonic about Vlad. He was, after all, a Christian. I highly doubt you get demonic power from establishing monasteries and improving agricultural output among the peasantry. Do you become 'evil' after you level up by killing so many Turks?
Or we can have Bram Stoker's hardcore, love-sick allegory for feeling guilty about sex.
And that's certainly not very gritty!
Anyways, to suggest that Castlevania needs to take itself seriously if it wants to be successful in 3D really doesn't make any sense. Look how successful grim, serious DMC2 was compared to the campy DMC1 or DMC3. Serious Dante in Serious Sequel nearly offed the franchise by the second game. People wanted the pizza-eating, "FLOCK OFF FEATHER-FACE" Dante, and DMC1 and 3 are regarded as some of the finest 3D action games today. The first one certainly rendered LoI hollow.
Castlevania really isn't God of War with its blood and admittedly unaware corny plot. Castlevania shouldn't have to imitate other 3D action games and desperately try to whore itself out to Rated M for Mature people. A successful series is built upon its own merits; namely how fun it is, not by how much gore it has or how seriously it takes itself.
If Castlevania is going to have a successful life in 3D, it needs to be fun. It needs to be addicting. It needs to be designed well. If Castlevania fulfills those criteria, then that will be a successful 3D game.
However, if Castlevania made another nod to Nosferatu (besides Count Olrox) by giving Dracula his repulsive characteristics rather than a romantic, gentlemanly count, then that'd be a great start to a more threatening Dracula. On the flip side, you could also wind up with naked blue Dracula from the comics.