Until we get further details I'd be willing to bet the non FC airships from Ishgard will be restricted in some way. Won't have access to the best islands or something. Probably cost a hefty fee to use etc. And if these end up like hunts with good rewards it'll just be a repeat of hunts. Big FCs will dominate the islands with the best farming. This is going to be a cluster.... just like any open world content. Too many people wanting to do it and not enough space to do it in.