For things you can do inside current divinty 2 build? Letting your abilities go higer then 5 (making them stronger), making the dragon friend summon more then 1 friend at higher levels, making the shield absorb more, giving you more general survivability in dragon form\ nerfing those few over powered commander opponents that do most of the dmg and increasing your fire range. Making opponents more aggersive into getting close to you instead of trying to fly away from you. Going a bit further you can add some sort of a claw skill to attack close units, sort of maybe grab your enemy and tear it or something but that would be more then a mere little balance patch. Also tweaking the dragon animations (which are pretty impressive right now) into feeling more natural (especially when flying backwards), but animations with your human form are in a greater need of work as it is anyway.
Again, the thing is I treat it as some sort of an arcade mini-game. Its like those moments in many FPS games where you "get" to control some sort of a stationarity strong weapon on a moving buggy and kill hoards of enemies, they aren't really fun more then the usual game and probably even a bit less, they're just there. Thou D2 dragon combat I did find fun actually.
But ill count on larian to come up with something claver for this in D3, if there is indeed dragon form and all. I am actually hoping for some sort of a glide function like that of Aion, or a stylish pair of wings for traveling (like those you have in Darksiders, I love those wings) instead of actually even turning into a dragon form for exploring purpose, while action segments for combat can be done in special pre-determent events\ places. Breaking the dragon form into traveling\ exploring and fighting gives larian a much better control and ability to come up with something fun and engaging without worrying about balance. Dragon combat should have been handled this way from the start in my opinion, like a true little segments that breaks up the traditional rpg style gameplay and give you some relaxment and little fray enjoyment, something different and new that is also there for story purpses. Even all bosses can have pahes for this, fighting partly in dragon form and partly in human form (like those old school platforming bosses, where you need to trigger 3 things to make the boss vulnerable?) Maybe, say, ur fighting a necro who decided, at 10% hp, to blow up the top of the cave and let some nasty undead birds in to kill you (letting you also take on dragon form), and after you kill those you give him the final hit (he has 10% so what does it matter) in dragon form. Dragon form dosent even need to be calculated with states and gear or whatever, its just something to juice up the fight.
Oh, I wrote a bit to much :P