The model you've seen isn't final, so in that sense it is a nifty consequence of looking at data-mined art. Also, unless you get very close to besting Ragnaros on Heroic difficulty, you will only fight him while he's in his usual, cozy lava jacuzzi. ;)
So basically, the challenge on heroic mode is going to be to keep the raid from falling apart because everyone's laughing at how ridiculous Rag suddenly now looks?
Haha... I want to come back with a defensive retort, but such a twist in game mechanics would certainly throw off even the most competitive of raiding guilds. Zarhym likes.