I don't see it being updated until Thunderbolt 5 is released. A 5K 120Hz panel would require more bandwidth than TB4 can carry, so there's not much else Apple can do to the ASD until then. And then that still depends on if/when LG can make a 5K 120Hz panel.
I suspect the XDR will be first in line for an update, but again will require TB5 to be a thing before it can be updated.
My personal prediction is no updates until sometime in 2025. And since 2024 is just getting started, you're going to have a long wait.