The interface seems to be “access to cameras through a variety of APIs”, where that currently means video4linux plus some extra VideoCore access that seems to be Raspberry Pi specific. Presumably if people needed access to yet another camera capture API (Firewire access for dvgrab?) it would be added to this interface.
Of course, the interface does nothing to distinguish camera and non-camera V4L devices (e.g. mem2mem codecs, TV tuners, etc). It’s not clear such filtering will ever be added, so it is probably the right choice for apps needing access to non-camera V4L devices despite its name.
Long term, I suspect we’ll probably see camera access for most desktop apps migrate to PipeWire, with just-in-time decisions about access to specific hardware rather than ahead of time interface connection.