Kobolds may have a large (or loud/ active) fan base here on the forums. But a new race should be attractive to new/ casual players too imho. A new race that a couple of insiders love is OK, but a new race that all players would like to play would be even better. In terms of marketing I would see more potential with Tieflings, Genasis or Chapeshifters. The last one would fit good to the eberron lore too. Perhaps playable Koblolds whould make a great reward for the last tier of favor reward someday?