I think what the developers tried to do with the change of format, introducing this mix of different games is a sign of wanting to freshen up the series, a series which had a very defined platformer line to begin, then separated into the 3d tipe platformers and the 2d rpg tipes. Changes that proved CAstlevania had potential for survival and for change. Because, what i think is at the core of any CAstlevania experience was the ambience, the dark, sadistic but sometimes glamorous vampire world, where you had this more basic tales of prime good and evil in the early games that evolved into more inmersing, dark toned, victorian worlds and complex gameplay. A think if any game model could be a good idea for the next Castlevania game would be something in the lines of Demon Souls, but with with an exploration on jumping mechanics that made posible keeping alive platforming aspects. But definitley i think it would be a good fit, and a very exiting possibility.