The only park affected will be MK that will close probably around 6 or 7pm as Grad Nites usually begin around 9pm.All the other parks should have pretty normal hours.I just checked and EPCOT has it's normal hours until 9pm, DHS is also open until 9pm and AK is closing at 5pm which is a pretty normal closing time for slower days as on busier days AK isn't really open that much later,even in July the closing times are 6 and 7pm.Also remember that EPCOT shows a 7pm Future World closing time and 9pm for World Showcase but all the major attractions in Future World also remain open until 9pm.