I take it you'd put a wide deviation around the (central?) 10k figure.

I would. We can see the 10k figure warping and changing over time just for highly specific expertises, like for chess - it's a regular bit of media coverage how grandmasters seem to be getting younger and (real time) less experienced, but still as good as ever.

(It's also interesting to note that at the same time as human grandmaster play becomes easier to acquire, truly high-level play has ceased to be just humans and become teams of computers & humans.)

I'd like to see what happens with people who are recreational athletes (basketball, volleyball, softball, etc.), not especially gifted in physical attributes, some of whom definitely log the 10k hours. Will it be accurate to say that those who actually drilled and rationally worked on specific skills based on analysis of their game performance, should be masters (limited from being pro-level only by their physical handicap)?

I know of nothing to the contrary. The Cambridge Handbook of expertise mentions that experts are made only by deliberate experimental practice, and that mere experience does not suffice; that amateurs can spend multiple decades at something and because their experience is not the right sort of experience, remain at their plateau.