A fork for the time-zone database?

Yes, it wouldn't just be resetting all the clocks in the world: there would be many logs and datasets to convert initially. However, once all dates and timestamps are converted to UTC, "timezone data" ceases to mean anything practical in the present, past, or future: a recorded timestamp was either _the_ universally correct time or not. Not that the histories would be discarded or completely meaningless, but they would become completely academic: history books of legislative trivia, not something you might expect to grapple with during your next automated software update. :-)

And whether the time of events is recorded accurately is the responsibility of whoever maintains the records, not the IANA: if my system clock is incorrect by several years (which does happen from time to time, especially after certain types of power loss), so none of the timestamps on my system happen to be accurate to any reasonable degree despite any political decree, that's only my fault and not visible to any external organization.

Similarly, many "hours of operation" signs would need to be reprinted to account for seasonal variance in opening/closing time of stores, etc., since local "daylight savings" would no longer be achieved by arbitrarily manipulating our timepieces. A store could open at 4 P.M. instead of 5 P.M. (and close at 0 A.M. instead of 1 A.M.) depending on the season.