The length of a noon-to-noon day (synodic day) varies from +29.9 seconds near the winter solstice to −21.3 seconds near the autumnal equinox[1]. If you account for the seasonal changes, you get closer to the ideal solar day which only deviates by milliseconds from 86400 s, but that deviation does pile up and "forces" leap seconds. I say "forces" because it's a legal requirement that the time tracks the sun.
Going to leap hours I think is a sufficient kick of the can down the road, one is only needed every few centuries. Pretty sure something'll happen in the next 600 years that obviates the need for that though (nuclear war, asteroid, technological singularity, need for a unified solar system time...), so us hack programmers can assume all three of those things.