So once these are out, will some people (everyone?) be no longer fully vaccinated?
Many vaccines have a recurrence schedule and if you aren't current, you aren't vaccinated for that thing. This reflects the reality of how vaccines and the immune system work.
Because of the public health situation involving it, being current with COVID-19 vaccination is perhaps more impactful for most people than, say, whether your tetanus vaccine is current, but it's conceptually the same thing.