The committee has considered whether there would be a need for boosters for ongoing vaccine supply. That is not clear, I would say, as a scientific consensus.
People are preparing for several trajectories, namely, that there would be a need for ongoing yearly boosters, that the virus might attenuate and only certain populations would need to have a new vaccination, or that it could fade away. You have to prepare for every possibility, the worst-case scenario meaning ongoing vaccine supply.