not quite, From what I can tell, you'll work to 80, do the quest, and then when you make a new character you'll have the option of picking death knight, who will START between 55-70
So its a completely different class? It would seem a little unusual to have someone invest the time and effort into getting their main to 80 only to force them to start a brand new guy and dump them into level 55-70 with no gear, money or mount.
I was under the impression becoming a Death Knight was really just a fancy way of bestowing one (a few?) Epic power(s) upon your guy that would be tailored to synergize with your current class.
I like my theory better then yours.
well from what we can tell, they only have the one hero class. That class isn't exactly going to synergize with, say, a rogue or warrior because he doesn't even have energy or rage to pull off the more powerful moves in either class.
My guess is that you'd probably have the newbie zone run for alot longer than most in order to get a Deathknight familiarized with his abilities, and it'd have some ok greens in it, maybe a blue sword, but ultimatly when it finished the deathknight would run off to hellfire peninsula or somthing to fight.