SD licenses the API on a per user basis. Using Philo as an example, they offer a local channels add-on for say $5/month (I'd certainly pay that). Start the negotiation with a 50/50 spilt on that revenue. Both companies get an ongoing revenue stream.
… I wish it would be that way. however my experiences are that vast majority does not want to spend a penny unless they must and would scream about those greedy companies , I have seen this way too many times. "can you imagine how greedy these <expletive> are?? I already pay for my internet, pay for my streaming service (Netflix, philo,etc) , paid for my tuner, pay for my DVR service and NOW THEY WANT FOR ME TO PAY AGAIN?!?! just to make what I already paid for multiple times to work together! I am triple charged here! " cue the media for the evil corporations, cue the lawsuit threats under freedom of this or that, cue the letters to every possible regulator, etc.
in reality, unless market is really there and is big enough, there is little value to engage in something like this as effort must involve return to sustain itself..