We will never be able to de-anonymize all Tor users

No, but the implication is that they may be able to do a lot of it, and we can never know.

What came just a few pages later in the presentation you referenced is "Goal: expand number of nodes we have access to".

That has been their goal for practically decades at this point.

Is it really some conspiracy-nut level stretch to think they might be operating thousands of nodes today and have much deeper penetration than we think?