assuming scheduled departure time is 11:59pm or earlier on 12/31, yes, of course, will count to 2024 PQP. If it is delayed past midnight, even significantly, it still counts as accrual is based on scheduled departure time.

however, if the flight is canceled and you are rebooked on a flight after midnight, that is where things are tricky. If you are able to rebook on a flight before midnight, also a nonstop, you’d be good. If it becomes a connection with second segment on 1/1, the PQP will get split, but no one can say by how much. If you are just rebooked on a different flight 1/1, those will be 2025 PQP. You may want to have a backup plan in case (PQP accelerator, for example). However, in case of the latter scenarios, you’d probably have a case to call in and ask for ORC. While I’d say the chances are good that it’s granted, you wouldn’t know the outcome for sure until it is too late to make up for it (there’s usually a chance to buy the remaining needed after the new year, but those offers are typically pretty exorbitant, especially as they know how important it is for some and they can…). Honestly, just in case, I might plan a quick trip with whatever you need - the very last minute trip to qualify is a risk due to the admittedly small but also high impact, chance of cancelation and not being able to rebook prior to midnight.

just my 2 cents.