There's no way we're behind gyms. From memory, they were closed during our last period of being able to fly with both leisure and modular commercial students, when our leisure PPLs were allowed to fly too. That's not to say I think we'll be back to that quickly, but you never know. Teaching people to fly is education after all.
I say keep your eye open for the driving instructors and driving test examiners to be out in force again (they're only doing key workers at the mo.) All the examiners are paid out of our taxes, so the DfT will want them back doing 7 tests per day, to get those test fees rolling in asap.
That's how I saw it coming last year, since they're in roughly the same confined space. Although I suspect there's far more fresh air coming through all the gaps in our aircraft cockpits.