I think that the aggregation model would have to go low cost, high volume, and not try to compete with the content producers. It would probably have to be a new entrant into the market.
The problem that HBO, Showtime, Starz, and Netflix all have is high legacy subscription pricing, which is hard to sustain given how modest their content libraries are. AMC has the added issue of being dependent on cable fees.
It is so easy for content producers to go direct that the value of an aggregator "brand" is negligible. On the other hand, consumers don't want to pay 10 subscriptions, so a single login and place to stream a wide variety of content has some value. Maybe there are 2 or 3 of those, and content producers are paid based on views or something. Like I said, I don't have the answer, but I do know the entertainment industry will be very different in 10 years.