I plan on running an Eberron campaign and may end up doing it in 4th ed, but am interested in preserving the story of 3.5 Eberron. IMO Dragonborn should not be common in Khorvaire and would be at best exclusively something out of Argonnessen. Would their be any major impact in the books if I removed the presence of Dragonborn altogether from Khorvaire, or will key characters in the new world be removed?
For extra credit: Would their be any other confusions if I tried to run Eberron in a 3.5 style story but give the players the 4th ed books?