To put this one in perspective, we already make vaccinations mandatory for public school attendance, and colleges go one step further and require vaccinations for attendance, too.
Both of those factors make COVID vaccination quite different from, say, measles vaccination (~97% prevention, lifelong immunity), and seemingly more similar to the flu vaccine, which is not required by any schools (that I know of).
As to the time the immunity lasts, that remains to be seen. Since it is brand-new, we will only know when new cases from previously-vaccinated people pop up. Maybe it'll be yearly, maybe a booster every 10 years, maybe lifelong. There is research showing that the antibodies from a corona infection last about half a year, but that is not the only factor that may provide immunity. And the yearly flu shot is because the flu virus mutates very rapidly, which corona doesn't as much.