Limited lab access is a lot easier to safely implement with shift reservations and people looking after each others projects than classes, so I'd expect that to happen to a degree. At least some universities here in Germany already do allow occasional lab access if needed, with appropriate precautions.
I know a few grad students at 'closed' campuses currently. Though the admin says the labs are off limits, the PIs are turning blind eyes to it. The labs are effectively open.
At the school where I work, they disabled key card access for everyone campuswide. You need to special permission to have them unlock it for a limited time period to get in.
Of course a few old buildings still use regular keys so people can sneak in potentially.