If Netflix went to in-house only, then they could significantly (I assume) drop the price. Part of Netflix's big expense is licensing content. If all of the major players are pulling content, then the licensing costs for all of that content disappears as well.
With shared accounts, the price is already pretty low at ~3-4€/person/month. I don't think that a price drop would adequately compensate for a significant loss in content at such a low price point.
Yes, in the long run producing their own content will be cheaper. Mid-term buying proven content will probably come out at around the same price as producing new content that the viewers may or may not like. They have better viewer analytics and better ways to globally monetize the content than traditional content producers though.
Hrmmm... 110,000,000 subscriptions x $5 = $550,000,000
Netflix sees that math every single month, and charge more that $5, and can always raise their rates again. They have something better than cash, they have recurring cash payments.
Also, Netflix is running less debt than its hollywood contemporaries who have no such subscriber base, no industry leading tech, no well-oiled IT machine, and no massive pool of user data showing the intensely valuable and intensely detailed interactions between hundreds of millions of people and their content with a decades head start on the competition.
