The spike in applications, I suspect, had multiple causes: test optional apps, more free time in a lockdown world, etc. but I think a lot of came down to increased uncertainty. Some of that will go away as some variables are removed, but some will stay. Reducing uncertainty should reduce the number of applications and make the process more efficient all around.
I think a natural solution would be to have more rolling admissions, EA notification windows or ED options (I, II, III) for more schools. More ‘likely’ letters. Earlier notification for clear rejections. Anything that lets the applicants know something sooner should help reduce uncertainty and that, in turn, should reduce the pressure to send applications to every school.