Here's what I'd like to see them do: Put out a Castlevania 25th Anniversary Retrospective Box Set. It'd include on one or two discs all the NES, SNES, Genesis, GB, GBA, N64, PCE, and PSX games. Basically games that are hard to find and that most fans have to resort to using emulators to be able to play. They could have graphics filters or use minor graphical retouching for them so they look a little better on modern setups, have menus that file the games by system, and have some sort of information (or perhaps interviews with the producers/creators) about the making of the games.
What this would do is make the older back catalog readily available. Konami gets to cash in on previous hits and the community has a standard of being able to play the older games on newer systems without having to resort to emulation. This might not even have to be made a physical release, they could do it on PSN, XBL, and whatever the online marketplace for the Wii is, though a physical release WOULD be pretty cool.
And at the same time, they could be preparing for the next original 3D release.