Not everyone who goes to Mass is “devout”. Some Catholics are less invested in their Faith than others. Some pray every day, and others pray only occasionally. It’s a matter of degrees. When you have been away from Mass for a number of weeks or months, and you get used to not attending, what happens when Mass is available again? Some persons will not return to Mass. It’s inevitable. It’s fallen human nature.
Some parishes were already struggling financially. They will have less money, because people generally only donate when they go to Mass. If this goes on for much longer, the pandemic is going to collapse some parishes, even some dioceses.
If the worst case scenario occurs, and 10 to 20% of the U.S. population becomes ill, we could lose many of our priests. The elderly and men die in higher proportions than younger adults or children and women. That puts our priestly population at greatly increased risk.
People do not realize that, “after” the pandemic, life will not go back to normal. This disease has terrible after effects, like lung fibrosis and CNS damage. And the effects on society will not go away anytime soon.