No, I don't think they'll release this, or if they do, not for a long time. Nintendo has a way of not coming back to old events for years, keeping you on edge until you've given up. And when they do release it, you'll wonder why they didn't do this earlier.
What I don't understand is, why didn't they bring the Azure Flute into Platinum for us Platinum players? I didn't have Diamond or Pearl at the time this event happened, and I still don't - I just have Platinum - so for me this wasn't entirely fair D:
I had to get my Arceus via a trade with a friend of mine. At this point I just don't really care how I get one, as long as it doesn't mess up my game and as long as it fills my Pokedex.