I suspect that FSD will take us by surprise and the actual transition to FSD will be murky because of how Tesla rolls out features incrementally over time. And I suspect that folks here won't agree on when AP becomes FSD.
I envision the roll out might look something like this: AP is not FSD now of course. Tesla releases "stopping at red lights and stop signs" but that won't make AP into FSD. Then, maybe Tesla releases "City NOA" and AP can take turns at intersections. At that point, some might start saying that AP is really starting to look like FSD since it can handle traffic lights and intersections on city streets but the majority will dismiss it. AP will require driver attention and will have some cases it can't handle well. So it still won't be FSD. Maybe Tesla implements "emergency vehicle response" where AP can yield and pull over for emergency vehicles. Great but there are still some cases that AP can't handle so folks will say it is still not FSD yet. But eventually, Tesla keeps improving the reliability, adding new features incrementally. And then one day, folks go "wow, AP is really good now and really is driving me everywhere with no issues at all. It is FSD! How did that happen?"