HBO's CEO has hinted at the possibility of a standalone HBO GO subscription... It's probably coming. One of the challenges to this is the way that deals are structured, and this isn't a bunch of executives sitting around wringing their hands and twirling their mustaches. There are certain agreements that content providers have made with carriers because they didn't initially have as many options for distribution as the internet has made possible in today's world.
The other challenge is... so you've got these existing revenue streams out there. How do you structure your content distribution in a way that doesn't cannibalize the sales that will piss off the carriers who depend on a cut of the monthly fees they charge?
While Lombardo understands that "free" isn't an option, he's as shrewd as Steve Jobs in treating "free" as a competitor and trying to figure out what they need to do to make paid HBO as compelling. What the iTunes model did was treat "free" as a competitor and then go after a more convenient user experience and one-touch purchasing.
The point that's often missed in a lot of the moaning about "users want free so it should be free"... no. Free is not the thing that the users want. If I gave you a pile of trash for free, would that satisfy your appetite for Game of Thrones? It's the content they want. But all of these defined revenue streams instead of an ad-based model (which is the "free" alternative in the pragmatic world of content production) are a large part of why HBO can produce the extremely expensive-budget shows with fewer episodes and better writing than the ad-based models that have to appeal to the broadest, dumbest audience possible.
If those revenue streams are eliminated, there's no cushion for them to commit to shows that would never survive on network television. The only thing they need to do here is to research just how much their cable subscriptions would be affected by online, and perhaps make a deal with the cable companies to compensate their existing agreements the way Apple paid the content producers upwards of $150 million to secure unlimited cloud streaming.
Something will get worked out because every party has an interest... HBO could very well serve up a pile of crap and not care as long as they got their fees. That's how subscription cable works, and through advertising it's how networks work. But they're not the Wal-Mart of television programming nor do they want to be. If they were, none of us would be here talking about wanting TV shows that some nonexistent premium channel doesn't produce that you've never heard of.