I am extremely skeptical of this whole 4-camera vs 8-camera thing. I think they just wanted something quantitative in the bullet points for FSD vs EAP for marketing purposes. When I look at the feature set of EAP vs FSD, those features need roughly the same sensor inputs. The long camera, for example, is critical at high speeds where both EAP and FSD operate. The side cameras (both forward- and rear-facing) are equally important to EAP and FSD for lane changing, "smart summon", curvy roads ("EAP+"). The ones I can see being useful for FSD but less so for EAP are the fisheyes (front and rear). FSD needs the forward fisheye in particular when entering an unprotected intersection (e.g., side road T intersection to main road) to see traffic approaching from the sides.
In the end, even EAP is hard enough to do well that they will want to make use of every useful camera, regardless of what the BS marketing was. The possible exception would be if there's not enough GPU horsepower in there right now (which there isn't). In this case, FSD may get hardware upgrades (presumably free) but not EAP, and then EAP would be constrained to a more limited set of cameras by GPU capacity. Even so, I would expect it to change which cameras it's using at any point in time -- for smart summon or EAP+ on curvy roads, the fisheye is way more useful than the long forward camera, so I'd expect them to use them. But then at highway speeds, the fisheye is less useful whereas the long camera is essential. It may briefly turn on either the fisheye or the B-pillar (side-forward) cameras during lane changes.