@Stephlovesinatra--I feel for your daughter. This is such a difficult time to be planning anything, even something 6 months from now. No one has a crystal ball. Who knows what will be the case in December? Or even next March? Will there be a second wave of the coronavirus? Or a vaccine? Impossible to know.
If your daughter can plan this and the majority of the trip is refundable, then maybe it's not such a big deal. But if we're talking about nonrefundable airfares, hotel rooms, food, wedding events, etc., then perhaps planning for something expensive in December isn't such a great idea right now.
I do think your daughter should be prepared for this not to happen. She can always get married in a small ceremony in December and then have a party at Aulani after things return to the pre-covid world. That might not seem ideal, but she and her future husband and their commitment to each other and lives together are way more important than the venue.