Yeah we know that he lives on Akavir,but alduin is summmoning the Dragons to aid him agaisn't Dovakhiin So there's a chance to fight an Super Ultra Cool Tiger Dragon of 50 foot like Tosh Raka?Or maybe in a Dlc?Ok he maybe not be a "true dragon"(because he was a Ka'Po'Tun that turned into dragon).Also let's not forget his disire to invade "Tamriel itself".
http://fc08.deviantart.net/fs71/f/2010/363/0/f/dovahkiin_fights_tosh_raka_by_1rich1-d35yh1k.jpg