They survived the Great Recession with making adjustments to routes that definitely weren't performing (MED feeders, 696/699, 767, UP-W Feeders, etc). You have to right size the operations so that you get the ridership that exists (and conversely, prevent the death cycle). You could request a temporary pause of grant funds for extenuating circumstances (655 and 889 were reused for 895). Since 2011, Service Planning had made efforts to adjust and make leaner changes to service so that the core network (30 routes comprise of roughly 70% of the ridership plus needed connectors). If ridership drops like it has been for the last eight months, then you make continual adjustments. Same with the satellite cities.
Case in point here: AC Transit has suspended their Transbay Routes in March 2020 only to bring back a handful of trips in August, and basically working 70% of pre-COVID levels across the board. Ridership has started to track upward; including the students at Cal (who choose to stay on campus).
Pace can and will manage this (at one point, not really the agency that got as much support from the RTA). Remember: agencies aren't out to make a profit and one has to operate service based on the ridership they have.