For the 25th anniversary Konami should just give us collections, maybe in two (or even three) volumes to fit everything (at least the good stuff). IGA used to say that a collection would be difficult because the games are scattered across so many different platforms. And while I don't know much about game developing I do know that other companies have done collections, so I think it's a lame excuse.
Chances are something like this wouldn't sell a lot, but the budget for putting a couple of emulated Castlevania games on a PS3/360 disc cannot be bigger than the budget for Castlevania Judgment. And that game bombed.
Anyway, my guess is Konami won't celebrate at all. Maybe we'll see a 3DS Castlevania announced at E3, but nothing out of the ordinary.