something to look forward to on heroic instead of the difficulty just being higher

In terms of storytelling and content accessibility, there isn't a real difficulty. The way we handled Ragnaros was kind of unique, but he's not the final boss of this expansion.

Your idea is quite contrary to wow gold fr our motivation for implementing multiple difficulties. We want as many people as possible to be able to experience the story, while still preserving many of the more prestigious rewards and achievements for those who complete Heroic difficulty.