On one hand, maybe Kojima style story telling would mean regaining CV's "playful" nature that has been severely down-played in recent years. Older titles were quite aware of their B-movie heritage, and had fun with it. But more recently, and especially under IGA's regime, that wasn't so much the case. I could definitely stand to see that aspect of CV return in style.
On the other though...I already don't like how IGA did more to make CV "serious" as it's been in recent years. I completely abhor the idea of Kojima and co trying to do anything akin to making CV into as much of a nonsensical mindfuck as MGS currently is.
i don't know what Castlevanias you've been playing. cause all the Metroidvanias have a sense of humor to them, save OoE. i mean, Portrait of Ruin does not take itself seriously at all. and all the other games have had the same little funny bits. whether it be descriptions for the Wacky Food Items, accessories, etc., or the Press It and See room and Chair Room in Curse of Darkness, or the Skeleton form in CotM.
in fact, the games have only gotten funnier since the series has gone on. the NES and Christopher games have no humor to them at all, actually, save for the dinky enemy names in CV1's localization. it wasn't until SCIV did funny things show up in actual gameplay. and it's rarely been in the forefront; most of the time, Castlevania humor is rather subtle.
CV is as serious now as it was on the NES. IGA didn't make the games more serious. quite the opposite, actually. a lot of the humor in the series comes from his development team. the only game that could top PoR's humor department is Rondo of Blood, but that's the exception to the rule.
too long don't read version: YOU'RE WRONG
and don't worry about Kojima mindfucking the franchise. it hasn't been said that his team is completely responsible for the project. he can't have the same amount of creative control as he does with MGS, his franchise.