In some cases, it might be preferable to have a question that doesn’t resolve until after the event happens, whenever that might be. Rather than on a specific date. In which case we would need open ended questions.
This could effectively be accomplished with early resolution and an expiry date that is effectively infinite (1,000 years or something).
The usecase I see this being good for is markets like “which will happen first, A or B?”
It may also be useful for insurance-style markets.