It would be neat (and probably a longer game) to try playing the game as if Colonies were the new Province card, and that Provinces were normal vp cards. In other words, the game end condition would be: empty any 3 piles OR empty the colony pile.
With my roommate we play like this since forever because he misread the rules and I didn't notice until today. It works well. We tried the normal rule and he finds it less fun.