As much as I have never really been intrigued by Darksiders because of the art style used in the first two games, that combat footage seriously has me considering buying this one at least. And I could totally see that being the basis of a 3D Castlevania.
Sadly, I hate to be the one to point out the obvious, but didn't Devil May Cry effectively perfect this style of gameplay way back in 2001? I mean, Lament of Innocence, God Of War, and even Darksiders all essentially just use tweaked variations on that theme. Actually, if you play Devil May Cry with the mindset of it being a Castlevania game, the first game REALLY GIVES OFF THAT VIBE. Devil May Cry 2001 was essentially if Castlevania and Resident Evil had a baby. Yes, eventually it grew up into a bit of a street punk with a "don't tell me how to live my life" vibe, but that first game was to me TEXTBOOK Castlevania in all but name. Even had the platforming elements!
I do think Konami should look to this sort of stuff for more inspiration though.