If you read the full text on the trade website you will realise this is a consequence of moving from ancient (in IT terms) selling systems into the modern era (NDC technology be at the heart of the change).

NDC technology enables BA to have a much finer grained level of fares than linking just to fare classes. You already get this on many sites using NDC, including BA.com, where several different fares can map to the same letter class. The trade site goes on to say that the number of inventory buckets in F is going up from 5 to 6! Club World is increasing from 5 to 9 and economy from 11 to 25 (WT+ remains the same)!

The trade site also says semi-flexible F will be retained.

Question: how will BA make more profit from this. Answer: there will be more intermediate price points allowing BA to gain marginal revenue, by spreading inventory across a wider set of price points.

If this scheme is rolled out, as surely as it will be, the rules asbout GUF2 may have to change.