I think the boosters will primarily address the problems associated with variants of concern. Nobody knows for how long immunity is conferred by the current vaccines. We know people are still exhibiting immunity 8 months after their first vaccine in the trials. How much longer will that last, and are the memory cells still programmed to spark into life when required, are questions as yet unanswered.
It may be selfish, but I can't envisage the general public being willing to compromise the nation's virus status, no matter how great the need elsewhere. We care about other countries, but maybe not enough to risk the sacrifices we've made trying to contain this disease. It's an awful situation to comprehend because logic tells us none of us are safe until all are safe, unless we operate effectively closed countries like New Zealand and Australia. Is the UK willing to stop all international travel for years? I doubt it.
We should certainly be aiding countries with medical equipment, and assisting the ramping up of the vaccination program worldwide. This is no time for petty politics, lives are at stake. As we, like many countries, have over-ordered vaccines, hopefully we'll soon be in a position to divert our excess doses where they are most needed. I do wish Pfizer and Moderna were willing to sell their vaccines a bit cheaper, they are way out of the price range of the poorest countries.