There is a mod for GC2, I can't remember the name, but it allows minors to colonize and behave more or less like majors. I found that it really spiced up the game as minors could occasionally rise to become regional powers or even major players if they were dealt a good hand in the early game. Is this something we're likely to see in GC3?
An alternative method of advancement for minors might be the ability to form federations, or possibly mechanics similar to the city-states in Civ V.