It's solved to the level that additional changes and advancements won't make a major difference to the company as it is right now. Those advancements might end up being a major component later, but someone else could solve that problem and they could license it just about as easily. At this point Netflix is a multimedia company that runs their own infrastructure, not a tech company focused on delivering multimedia.

Netflix could swap out all the underlying tech for someone else's and update their players to use that and nobody would really notice, except possibly for the very few interactive experiences they run. That's why they're not a tech company anymore, they've matured the technology, and so have their competitors, to the point it's a commodity.