Closing is a risk but not as great as at Christmastime -- Easter has the advantage of having both waterparks open and being warm enough so that huge numbers go to them, usually preventing the theme parks from filling to capacity (although the waterparks often do). The 8 to midnight hours for MK plus the often extra hour in the morning for resort guests should help prevent the risk of closure at that park, the only one where the risk usually arises.