If the rumor is true and the dragonborn are core, I couldn't possibly be more disappointed.
First off, I don't really like dragonmen anyway. But then with the whole angle of "normal person crawls into an egg and emerges as a dragonman"? Yeah, no. Not at all.
Needless to say, they will be immediately stricken from my campaign barring any serious changes. I'm just disappointed that since they are a core race, they will be supported much more than other races that I don't absolutely hate, and therefore there's going to be an unfortunate amount of content that I will have to completely ignore.