I feel that the BBC Merlin, and the open-ended series finale is an untapped resource for Netflix. The fans are die hards who have been waiting 6 years for even a whisper of a 6th season, a film, anything that goes into Arthur's return to Merlin and the modern day world, and how they would integrate magic and the 'great kings of old' into the present. How was Merlin changed by the thousands of years he has walked the Earth? Is he cynical, does he still wait for Arthur to rise again? What modern day conflict would cause the magics of the Earth to return Arthur to the land of the living when there are so many potential triggers with the tragedies of today's world. 
If you put out a poll to establish interest you would undoubtedly get a response in the millions.

Of course there is the matter of getting the rights to pre-existing, original content, and roping Bradley, Colin and hopefully a few other familiar faces into returning, but it is something I think Netflix should strongly consider pursuing. 
They have saved and revived a number of fan-favorite tv shows, especially recently, and I think this particular show would be worth taking into consideration.

Return the Once and Future King!