Three months later, only one pilot from that list has been shot, as far as I know: NBC’s comedy Night School. The networks were faced with the same dilemma and, overwhelmingly, asked the studios to extend the options on the pilots. I hear the length of the extensions vary project by project, with most actors secured through June 2021, and some pilots going for a hold through December 2020.
The only pilot whose cast was not extended further is CBS comedy Jury Duty, which remains in consideration and could be revisited in 2021.