Covid-19 is clearly not going to vanish unless we a) produce a successful vaccine, and then b) commit to a worldwide coordinated eradication programme. Part a) is merely technically difficult, part b) requires sustained global cooperation. We did it for smallpox (intensified eradication programme started 1967, world declared free of smallpox in 1980), we started doing it with polio and achieved a lot – only endemic now in Afghanistan, Pakistan and Nigeria – but seem to be going backwards due to local wars and global disagreements. I can't see us getting anywhere near that with any new programme due to the shapes of global politics and culture, sadly.
But what really counts for rail (and bus and air etc) travel is not so much the existence of the disease as the epidemic outbreaks and our reactions.
You never know, SARS(Sister virus to COVID19) died out in 2005, anything is possible.