I`d agree with you on this one.I`ve seen an heard rumours surrounding Hammerfell as a possible DLC location by an ex Bethesda worker ( or so they claim ) http://vehq.net/skyrim-dlc-info-leaked even without these rumours,adding Hammerfell makes perfect sense,and there is plenty of clues scattered throughout the game to suggest it as a dlc contender.
I don't believe this leak... The Dragon are back for less than a year, and a guild has already
mastered the ability to tame them? Seriously, taming Dragons? We are about intelligent beings, thinking of themselves as superior to mortals. They'd probably prefer to die rather than to obey ! Enslavement would be a more accurate word... Besides, we now know that the first expansion won't be called "The Riders of Hammerfell"...
I'm calling B.S on that article. How the hell would we ride wolves?
Maybe it'd be a http://uesp.net/wiki/Arena:Monsters#Snow_Wolf, which is possibly bigger than average, and is said to be able to use frost magic? Or maybe it'd be a Daedric, presumably massive http://uesp.net/wiki/Arena:Monsters#Hell_Hound ? Since they love lava, they'd fit in Skyrim's Volcanic Tundra, in my opinion...