Based on both an article from the announcement time [1] and the wiki page [2] the Defenders are jointly produced by Marvel TV and ABC Studios, merely distributed by Netflix. If that is true[3], then Disney (which owns Marvel and ABC) owns the rights to them, and once the current contract expires Netflix will no longer be able to distribute (stream) any of the Defenders series.

That would apply to Agents of Shield as well, which is also part of the Disney family.

[1]:http://deadline.com/2013/11/disney-netflix-marvel-series-629... [2]: https://en.wikipedia.org/wiki/Jessica_Jones_(TV_series) https://en.wikipedia.org/wiki/Luke_Cage_(TV_series) [3]: You would need a lawyer to examine contract language to be 100% sure, but Disney has armies of really good lawyers and understands the importance of IP better than anyone else on the planet, so it is extremely plausible.