They are transient only in those rare domains that can be fully formalized/specified. Like chess. Anything that depends on the messy world of human - world interactions will require humans in the loop for translation and verification purposes.

From a human, to a centaur, to a pegasus, as it were.

How is chess not fully specified?

I'm guessing that they were referring to the depth of the decision tree able to be computed in a given amount of time?

In essence, it used to be (I have not stayed current) that the "AI" was limited on how many moves into the future it could use to determine which move was most optimal.

That limit means that it is impossible to determine all the possible moves and which is guaranteed to lead to a win. (The "best" than can be done is to have a Machine Learning algorithm choose the most likely set of moves that a human would take from the current state, and which of that set would most likely lead to a win.