There's a huge difference in Universal park attendance since those split park HHN days. IOA is packed both before and after HHN starts. It's inconceivable to think they could, or
would want to, pull this off operations wise....and....there's a huge increase in tourism that isn't related to HHN, all those people filling up those thousands of rooms that didn't exist
previously. Some are HHN guest related, but many are people that have only fleeting, or no interest, in HHN and want to spend the evening in one of the parks while on vacation.