If we don't bother with leap seconds, then the distance that the sun will be off from being directly overhead at the equinox is about the same as it is now from being a couple of hundred miles away from the meridian. A simpler solution to the problem would be to, every couple of thousand years, have a one-hour reset. There is basically nothing that depends on the position of the sun in the sky to that level of accuracy, but there are a huge number of things (including all air-traffic control systems) that depend on keeping time in sync to sub-second accuracy and are safety critical. These things all need some special handling for every adjustment and an extra hour would be no more difficult for them than an extra second, so doing one big correction every couple of thousand years would be far, far cheaper. That's of course assuming that we still care much for a time system that's predicated on a single planet's relationship to its star in 2,000 years. It seems likely that we'll either be sufficiently disbursed that we don't, or that we'll have damaged our civilisation enough that we will have far bigger problems to deal with.