The thing about Dragon Tribal is in 5C you get to play any of the 10 Dragonlord cards you want, Prosh, Scion, the Regents, the Tyrants, the Scalelords, the Elder Dragons, the Hellkites, etc., etc., etc.
In terms of new cards you should expect to see more enablers than anything else for the dragons deck, because they aren't really going to be able to print many new dragon creature cards that are legit going to be able to find a spot in a deck that's already having to cut like 220+ cards for not being good enough.
Vampires will have a similar issue, though not to the same extreme, because there's a shit-ton of crazy vampire cards already in the wild.