unrelated to leap seconds, more about time and frequency metrology in general, the BIPM is carefully working towards a new definition of the second based on optical frequency standards instead of caesium

https://www.bipm.org/en/-/2024-02-20-redefinition-second

the plan is to use a quantum transition that produces photons at a higher “optical” frequency than caesium’s 9.2GHz, which should make it possible to improve the precision of atomic clocks by a factor of 100 or more