Make a Simon's Quest style game, set it in 1999, have it star Julius, and bring back Masaki Hirooka for the art design.
If there was anything I adored about Ecclesia, it was the art design. It was the perfect style for a "Castlevania" game.
It was the perfect balance of the darker, barbaric gothic of the older games and the elegant, supernatural gothic of the previous metroidvanias. When I was walking around the locals, despite the supernatural elements, all the locations felt very real. Dracula's castle seemed like a real castle, just full of supernatural things. The character designs were also spectacular. The outfits were well designed but still somewhat realistic, not only for the time period, but they just looked like something someone would actually wear. Dracula had the young immortal feel and yet still felt very old, dark, and evil, and I found the lack of visually effeminate men refreshing.
Sure, it's an art style, and I love most of Kojima's work, but in my opinion, men should look like men. I see no reason why all these men younger than immortal have the facial structure of a woman in her mid thirties. Simon is completely ripped, but apparently his neck has a testosterone seal on it because his head is completely androgynous. The only thing that balances out their feminine traits is the fact that the women are HYPER feminized.
Not to say I don't love the detail and elegance of Kojima's artwork, I just think Masaki fits Castlevania much better.