I have no idea what BAC will do and don't trust anything I am told for reasons explained elsewhere (and I've been told entirely contradictory things by people credibly "in the know") but what I'm pretty certain about is that whatever will be decided will have absolutely nothing to do with the fear of annoying either those who will be lost or even less those who have "legitimately" requalified. Airlines do not do that. Ever.

The considerations will be how the numbers would look to people needed for the commodification of status to achieve its purpose (ie potential partners) and to an extent expected impact on future sales. If the idea is that by granting extensions to x people who didn't spend enough, those who did will stop spending out of annoyance, that is simply not going to happen.

Incidentally, BA have always granted extensions to people who do not requalify under a certain number of internal guidelines. I certainly cannot imagine that going away (and the numbers are not as insignificant as one might think) so the only question is how much beyond that they go and which categories or criteria would be used to apply such added generosity. From that point of view, it is also worth noting that "nett" numbers do not matter as much as "gross" numbers (ie how many people are being lost, regardless of whether they would be "replaced" by others whose long term behaviour is harder to predict).