This is the most nonsensical part to me. If the vaccine does what they say it does (reduce severe cases) then the justification for mask wearing and social distancing is gone.
As more people become vaccinated the transmission rate will drop rapidly and people will stop complying with masks and distancing, etc. Same thing that happened in the Northeast and West when the transmission rare was suppressed, people started acting more and more normal and things reopened. Except this time, they'll have good reason to.