There's an agreement to do something about leap seconds before 2035, either by allowing DUT1 to exceed its currently specified bounds (this is most likely) or by agreeing to simply not insert/delete leap seconds going forward (this is less likely). For certain bounds on DUT1 and at some timescale, these would be practically the same in terms of their effects on civilization, computing, etc. In any case, a decision will almost certainly be made much sooner than 2035, perhaps even before the next leap second insertion/deletion would need to take place under the present rules.