At its heart, the FF concept is about exploration. I really liked the term Imaginauts to describe them. Sure they are a family, but that's incidental.
Would an ongoing TV show be a better fit for them? They go on a trip to explore the mysteries of the galaxy, or the microverse, or the Negative Zone, or wherever?
Think Star Trek or Lost in Space, but with the core four. Would that be better and/or get around this Fox thing?
The only think that would concern me is the budget on a Netflix series and whether or not it could handle it. It could come off looking cheesy like a SyFy channel movie. But it could be a way to introduce the FF into the MCU, and that's assuming you mean Marvel getting the rights back. It would be interesting to see a multi parter about exploring the Negative Zone