[CyberRabbi]

UTC can never be set as a constant offset from TAI, it will eventually cease to be useful and that can never happen.

[tialaramex]

TAI is very useful. The thing people seem really anxious about is that it isn't directly tied to the Earth's rotation. But, like, so what?

[SAI_Peregrinus]

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.