I would be somewhat more comfortable with this if BA.4 and BA.5 had evolved from BA.2.12.1. But my understanding is they evolved from BA.2? As did BA.2.75, which is the new one gaining traction in Twitter chatter. A BA.4/5 descendent prediction could be spot on. Or that evolutionary branch could be well in the rear view mirror.
I believe that the WHO is recommending that the gen 2 booster be based on BA.1 for broader coverage of any Omicron descendent. Sounds like the US is betting on BA.4/5. 