If you work for Blizzard and say that the next expansion is going to be about dragons, you've already broken the NDA. If you work for Blizzard and tell someone that the expansion announcement is in Spring and the release date is slated for fall, you've broken the NDA. If you work for Blizzard and tell someone that the next expansion will feature cross-faction play and that the next class will be dragon-based and have 2 DPS and a healing spec, you've broken the NDA.
Saying that the names of the next race and class doesn't matter at that point. You've already given specifics and broken the NDA. Further, if this "source" is already spilling this amount of information, it's utterly ridiculous to believe that they won't say what the next race and class are called. Can we just take a moment here and think about this scenario?
You're talking to a dev and they're literally dumping info on you about the next expansion, you get to the next race and class, they tell you that they're both dragon based, that the class is DPS/Heal, but then they suddenly don't tell you what this class or race is called.
You seemingly don't care about this crucial detail, and since you care about your source, you don't want to pry any further. Not even a "Oh man, that new race and class sound cool! What are they called?" Nah, after this person pretty much puts their entire job on the line by breaking the NDA several times over, for some reason, the names of the next race and class is a bridge too far.
No! Instead you ask this person what's the status of Dark Rangers and Tinkers..... From which they continue to give you NDA-breaking information. To top ALL of this off, this guy who is so concerned about his source puts what the source told him on a public forum instead of just keeping it to himself. C'mon!