So right now Deathwing is flying all over and ganking innocent level 20's with his fire. My question to you guys is, Where DO YOU think his lair will be? Deepholm? Where he was originally. Or maybe Twilight Highlands, at Grim Batol. If you did the quest there you will know why maybe (not giving out spoilers for those who havnt done it.) Or he could be a last minute thing and be a single boss encounter in a portal below the wyrmrest temple (alexstrasza might catch him and prison him in there, you never know what crazy things blizzard might/will do.)
Maybe he will be a single world boss tuned for 40, Like Kazzak. When someone dies he gets stronger, stopping the groups of 80 killing him.