I have not tried dragonriding so I do not know how trivial makes the races, but it definitively should make regular flying trivial, but hopefully fun too. Still, I am confident in Blizzard to make challenging content even with the full talent tree, which should be completely optional for cosmetic stuff.
BTW after messing up with the new DH talent tree I think that they are... Pretty ok I guess? We knew that they were dividing a lot of things that we already have into talents, and the result is ok I think. Anyway, Vengeance is what interest me and is so sad that we do not have them yet.