Konami is definately making the right decision by taking the series 3D on PS2...
2D games haven't sold well on next gen platforms...Contra did not fare well...Klonoa 2 didn't either (although I loved that game)...
I hope they can include some really fancy particle effects not unlike ZOE2 quality, stylish artwork and a stunning musical score backed by a top-notch orchestra. Konami has a few TREMENDOUS graphic engines for the PS2, so visuals shouldn't be a concern...gameplay should be the main objective. Ratchet and Clank uses a great 'rope-swing' type system...so the whole wip/chain swing can be done quite well in 3D.
Konami (or at least Kojima) is known, in many people's eyes, as the creater of the best 3D boss battles. MGS would be the best example. I can see much more interesting boss battles in a 3D Castlevania than in a 2D Castlevania.
And like DH said, they could easily include effective RPG elements. I haven't played SOTN, so I don't know how those worked, but leveling up and finding useful items could be well implimented.
Can't wait for E3
