Netflix has several concerns up ahead which might make it difficult to survive operating at a constant loss. One is that Hulu and Amazon are encroaching on its markets, and competition tends to drive down profits. Another is that they don't own the vast majority of their content, which puts them at the mercy of the pricing of their suppliers -- and being downstream from a monopoly can also drive down profits. Even worse, their suppliers still have a revenue model based on this old advertising-and-cable-packages system, which Netflix is destroying by transforming the landscape: which is a disincentive to working with them; a channel which can broadcast a breakout-popular new TV show might keep that in-house to try to keep the channel alive, rather than licensing the show to Netflix for an alternative revenue stream. At the very least this will probably keep Netflix content about a season behind whatever's on TV.
Finally, Netflix is finding itself raising its own prices, which may lead to a flurry of cancellations from people who maintain inactive subscriptions precisely because they're pretty cheap. On the flip-side, it's not clear that they can sustain continued growth in their subscriber base; maybe at this point almost everybody who wants Netflix's service is already signed up. If those numbers don't keep up, then problems arise that are not too different from the problems with "borrowing from the future" in Ponzi schemes (albeit with a solid net positive revenue, which makes it morally very different -- in Ponzi schemes this is 0 and it is being advertised as a huge number, which is a huge lie -- no similar problem here). A similar "collapse" could happen, where the growth tapers, thereby skepticism spikes, thereby costs to borrow go high, and everything rapidly turns around from apparent success to apparent failure.
There may also be problems with the corporate culture, but while most of the article is devoted to the corporate culture, no clear message is given; it is apparently a somewhat ruthless place which is probably somewhat sad but is also sold as really exciting, because the ruthlessness only keeps the people who really care about what they're doing, which apparently creates good morale. There's a lot of other details like that which don't really amount to anything significant regarding what this "new world" is that Netflix has created, or whether it will survive the above growth pains.