Most likely. They could add leap minutes, hours, or days instead. But they'll probably set UTC as a constant offset from TAI, and let the few uses that care about accurate solar time use UT1.
If you want something tied to Earth's rotation, UT1 is the way to go. If you don't care, TAI is good. UTC is in a weird compromise position, where it (traditionally) tried to be within 1s of UT1 but otherwise tick at the same rate as TAI. That compromise turned out not to be what anyone needs, so future uses will probably pick between UT1 and TAI/GPS/Unix/some other fixed offset from TAI.