[bloppe]

> hard time jump every few thousands years

This is never going to happen. If handling 1 leap second every year or two is so hard and destructive, imagine the anxiety of introducing 30 all at once after 100 years of complacent software development with very few people alive who even remember the last adjustment. Of course our children will just say "screw that".

TAI always has 86400-second days. UTC can have 86401 (or 86399 theoretically, but that's never happened in practice). Eliminating leap seconds from UTC is so dumb because TAI already exists and is basically just UTC but without leap seconds. But, for some reason, the BIPM would rather allow UTC to drift from UT1, but it will always have the ~40 historical historical leap seconds that have already occurred. It will become a strictly weirder version of TAI.

I predict that in hundreds of years, as UTC-UT1 reaches several minutes, people will start talking about inventing a "new" time keeping standard with leap seconds to stay in sync with the Earth, and shift to using that for civil time keeping instead of drifty UTC. Then we'll finally be where we should have been the whole time: effectively using TAI as the source of truth, and converting to civil time by introducing leap seconds (but the new "TAI" will be weirder than the old TAI, which we should've just been using the whole time).