「JR西日本「危ういローカル線」はどこか。社長が今後のあり方に踏み込む | タビリス」:https://tabiris.com/archives/local-rail202002/
This is a more detailed report on JR West's announcement>>1611998
Of course it is not loss-making local lines that cause them become red, but lacking revenue from Shinkansen and long distance express trains cause them to have no money in excess to support those loss making local lines.>Stopping services during Corona looks acceptable at first glance.>The thing is, that would ultimately be used as an excused to close those lines down for good.
The problem is not excuse, but that the maintenance cost. Maintenance cost is the biggest cost fot low frequency local lines, if you pause service on a line but intended to continue using it in the future, you will still need to maintain it thus cannot save money, if you try to also pause the maintenance, then the maintenance bill will quickly adds up when you try to resume service, and will become economically unfeasible really quickly. Hence they aren't talking about suspension, instead permanent cut.>>1611901
as for buses, many smaller settlements serviced by local lines don't have buses in the forst place, so additional vehicles and drivers will be needed. Which actually is also a problem given the aging population in Japan.