Nobody really knows what will happen in practice, as it simply hasn't been forced yet. But the time is drawing nearer. Personally, I wouldn't want to be the hemepath or neuropath or whatever who drops AP and has to face the issue in a mixed general/specialty signout group, as they would not be board certified to sign out those general/non-specialty cases. Sure, they could do so like any non-boarded practitioner, but by the way we got a few calls from some AP+spec applicants for your job this week.
It may be that in practice no-one will care if you the non-APCP hemepath-only sign out a glioblastoma. But my understanding is that the ABP intends those with spec only certificates be limited to that spec -- as far as their actual authority goes, anyway. Paper comparisons of folks being all the rage, along with competition for specimens, competition for jobs, fear of litigation, insurance (not just the paying kind, but professional liability too), etc., I would want to be rather sure about matters before doing something rash like dropping a primary. That said, I doubt most AP+spec folks will intentionally drop AP, as most probably practice some general surg path anyway and it's probably not much skin off their backs to maintain it as compared to those without a spec. Some may drop CP, perhaps. And individuals in certain niche groups might drop AP, such as FP's. But it's -probably- a lot of talk about something that will only affect a small proportion of people, at least if the exam is as reasonable as is claimed..