Netflix is the faster, more nimble disrupter, and while HBO is not as stodgy as TWC (or other telco's), it will lose the game of both content creation and the scale required to negotiate attractive content deals.
I think you might be onto something -
better negotiated content deals would are actually key to acquiring more customers and scaling up. I've previously worked on film financing deals where everything hinged on being able to get cheaper financing for money for content creation.