Once things return to some sort of normal, I do worry about what will happen to the bus network, particularly in provincial areas outside of the main cities.
There has been lots of warnings to avoid public transport, further enforcing stereotypes that buses are dirty and full of germs. Of course, its good to avoid public transport at this moment, but when it is safer to travel, it will be in many people's mind about the spread of germs in public transport.
Most people who have no choice but to use buses will continue to do so. But this lockdown may have pushed some to finally get themselves a car. Many elderly and vulnerable people may have a second thought about getting the bus into town, in case they catch something. And, many businesses may have seen the benefits of home working, meaning less people commuting. One thing I can't see changing massively though is the amount of school children using the bus to school (although with more home working parents, there could be more lifts to school for pupils).
Less passengers will inevitably mean a drop in some frequencies, making the bus even less attractive. In Kent, pre-lockdown there were already routes where I am often the only passenger, or amongst a small handful of others - these routes are often contract routes so are safe in the short term, but councils may not want to justify continuing to pay for these routes. Commercial routes (a few of which are actually infrequent rural routes) may not return to their previous frequencies. Marginal routes may become loss-making.
These are all 'ifs' and 'buts', and i'm no expert, but I can't imagine passenger levels returning to how they were pre-lockdown.