Creating original content, as the article points out, is extremely expensive. Netflix is going into massive debt to create that content. When Disney+ launches, Netflix will presumably take a sizeable hit from migrating subscribers (I myself was just thinking I'll probably cut Netflix when Disney+ launches). Revenue goes down, debt goes up. That is a recipe for disaster. Can they sustain the hit?

I think the answer is yes, but it'll be interesting to see. Ultimately you're right: They've proven themselves to be nimble enough to adapt to lots of different landscapes.