LOL..
Posit a future event, any future event: Trump’s resignation, SMOD, my sons’ moving out ...
The two possibilities are (a) it will happen and (b) it won’t happen. That’s it. Sometimes there’s a time horizon. The possibility of Trump’s resigning exists only for the eight years he potentially could be president. The possibility of my sons’ moving out is relevant only in my lifetime: they can have the house once I’m dead. The possibility of a SMOD strike exists, in math at least, as long as there’s an Earth.