Well seeing as in it's not gonna be as long a wait as say The kanto remakes to D/P
I think that Platinum and HG/SS will come hand in hand There'll be some colaberation maybe.
I think Nintendo will want Platinum to be long living or at least as long as the DS
Yeah, if HeartGold and SoulSilver had to replace anything, it'll most likely replace the older versions of itself, like how FRLG got more people playing that over the old Red, Blue, and Yellow. Now, I'm not saying people won't still be playing the old games, but more than likely most people will prefer the remake simply because of new features and the new 3D look to it as well.