That's what we do in the Cyrus IMAP scheduler for future alarms. We set the trigger at most 30 days in the future, and at that point it will re-calculate when the alarm should fire. Using the tz database at the time each time around.

Of course, calendar events in icalendar have the tzdata stored along with them, in theory, so they should never change unless your client updates them. Which leads to its own world of fun.