I would have agreed with you until I myself had interests in the bay area and indeed established a base there. International in and out of SFO is (like me) the tech crowd. These are mostly Y-only or Y+-only travel policy customers. Some of us that travel regularly use J but would hardly ever pay for F. However, the tech crowd, until C-19 at least, travels a lot, have huge Avios or Miles balances and love to upgrade into F for „nothing“. I do the same myself, regularly using GUF to book into A class. It really does not surprise me that BA does not continue this.

Up to now, demand for SFO has justified the huge A388 which just happens to also have F, so availability is IMHO a side-effect of that. Now demand is gone, I cannot see F on that route for the forseeable future. And frankly, BA will not lose business as there is no direct competition offering F. VS J on the other hand might regain attractivity.