HBO right now has a huge lead in terms of content over Netflix. By dragging out the unleashing of HBO Go they are actually letting Netflix catch up to them. They know that untying themselves from Cable is their route in the long term but are dragging it out (probably because Comcast pays them handsomely for it). But by dragging it out they will hurt their long term attractiveness. It only takes bad bets on new content over a couple of years to make people doubt HBO, given Netflix is also making their own content now.