For as much as anybody here likes HBO, the diagnosis Stankey (and, I think, Sims) has of it seems apt. HBO has a sterling reputation. But so what? Even today, they're no longer distinctively good; in fact, there are basic cable channels (AMC and FX) that have given HBO a run for its money.
Does anyone really believe that HBO is going to outcompete Netflix on original programming over the long run? Netflix introduces new programs like Google introduces new chat programs. It's not even an event for them. They just randomly drop them in the middle of the week, as if they don't have time even to promote them. Have you ever started an episode of Jessica Jones and had to wait 2 minutes for them to promo the next season of Mindhunter?
And that's just Netflix. Amazon will eventually figure TV out. Disney controls Hulu now. Apple is making a move into online video.
Meanwhile, after Game of Thrones ends, what's HBO got for tentpole series? Westworld? Besides the fact that it won't be airing again for 2-3 years, its renewal was not even a certainty.
I think Stankey is right. If HBO is going to be a factor long-term, a thing people pay substantial amounts of money to retain access to, it is going to have to look more like Netflix and less like a thing you pay your cable company extra for. HBO could afford lulls of a year or two taking flyers on just 1-2 new prestige series (Carnivale; Newsroom; Vinyl). But premium cable is over, everything is going to be disintermediated, and HBO will need to justify demanding $15/mo directly from people. I'm not sure it's worth that today.