For a long time, the Pay TV world had a reliable division of labor. Itusedto look something like this:

Film and TV studios generated content. Aggregators purchased this content and packaged it in the form of linear TV channels. TV operators acquired channels and offered it to viewers by means of a set-top box. But gradually, this model changed. Aggregators began to create and distribute their own content. STB manufacturers became distributors. But the biggest change, the one that has blown the doors off the old model, is the introduction of unmanaged networks, also known as OTT (Over the Top), into the viewing space.

What is OTT? It's any content delivered over the internet, but outside a managed network such as the ones your local cable or satellite operator provide. It's YouTube, Hulu, Netflix, and countless other video providers. They're wildly popular, and they provide content on any device. You probably don't need statistics to see how widespread these video sites have become -you can see it with your own eyes -but here's some anyway:

-Between Q1 2011 and Q1 2013, online viewing has increased 50-100%across most age groups, while over the same period linear viewing has remained relatively stagnant.

-In the past four years, Netflix Streaming has grown from 3.7 to 31.1 million subscribers in the U.S. alone, making them substantially larger than leading Pay-TV service providers in the U.S.For decision-makers in the Pay TV industry, OTT is an undeniable new force that demands attention. Is it here to stay? That seems certain. Will these increasingly popular sites steal Pay TV's lunch? Well, probably not. Here are four reasons why:

(1) Security-a pay TV deployment usually involves a managed network where the broadcast operator is involved throughout. The operator also manages secure transmission of content from the network to the hardware device used to display the content, such as a set-top box. Security, in this scenario, is strong. OTT delivered over an unmanaged network does not necessarily have this mechanism in place. Without security, anyone could access OTT content, leading to...

(2) Monetization-If the content is not secure, it will have far less value, since it can be freely acquired by all. This is not what content creators, who want to see a profit on their investment, have in mind. So offering unprotected premium content isn't a feasible business model. That leaves OTT content providers with two options: provide worse content, or protect premium content. Protecting premium content requires investment in network infrastructure, leading us right to...

(3) TV Everywhere Solutions-Broadcasters, who already have the network infrastructure in place to ensure broadcast quality, security and availability, are rapidly rolling out OTT-friendly features in their own product offerings. These offerings are multi-device, integrated with the familiar interface of a program guide, and guarantee the quality of service to which viewers have become accustomed.

(4) Quality of Service-OTT providers are highly reliant on IP infrastructures to deliver content to their subscribers. Operators own this infrastructure and therefore control bandwidth allocation. "Most subscribers take glitches, buffering delays and pixelation as given facts of life when they watch free videos," says Liran Tal, Strategic Analyst for SPVSS, "However, that is only true for free content like YouTube. For a pay service, people expect a premium QoS, which pure OTT players cannot provide. It is therefore not at all surprising that Netflix is now seeking partnership deals with the likes of Virgin Media and Comcast."

OTT isn't going anywhere, nor should it; from the viewer's perspective, the long tail of content and the ability to watch anywhere anytime are welcome developments. But as a sustainable long-term business model, OTT seems destined not to stand alone but rather merge into existing infrastructures with the capacity to make it profitable.