I’m quoting from the Current Known Issues list that are part of the announcement of AT:
More details were shared during podcast episode 298 (where AT was first announced), starting from 1:20:28.
So classification of outside workouts is planned to be part of AT. (Of course, I have no insider information and I am not arguing that it is definitely part of the initial release. That feature could be delayed to a future release.) Hope that helps.
I think I understand the difficulties very well: you are trying to characterize a ride with a few numbers. Nevertheless, it does not seem impossible: I think it is good evidence that I am improving VO2max power when I achieve a 3–5-minute power PR. To quantify that is hard. But then, it took TR >3 years to get to where they are now. And even if the measure they have come up with is imperfect, they could iterate on it.