Class dilution is a real issue for adaptations of D&D. A lot of modern CRPGs are trying to move away from class systems, because clearly there's a market for that kind of gameplay, and I love playing new RPG systems and exploring the different rulesets they bring to bear.
But creating characters in D&D is all about the things that make your class unique, and this is a D&D game. So please - please - please - let this game be for those of us who enjoy constraints (like the clear separation of arcane and divine magic) for the meaningful differences they can produce in a character.