As Nintendo only rarely repeats offerings of icon elements after their initial offering, especially for those associated with events, fans who don't want to miss out will need to make sure they've played the game at least once before the time period is up. The promotion ending in January should at least give people yet to receive the game for Christmas plenty of time to get their icons. As for anyone else not fortunate enough to get their own copies of the games before then, perhaps you can borrow someone's game via the Virtual Game Card system to quickly grab them before they're gone for good?