Taking a step back, isn't the history of the information era one where technologies get sequentially overwhelmed? Music has had at least two delivery systems swamped in about 25 years (Vinyl by the CD which was obliterated by internet-based delivery systems), IBM -> Microsoft -> google . . . I'm not a tech geek, but it would seem that eventually there will be a delivery system for baseball or other entertainment that will obliterate cable channels unless they drop fees as a barrier to entry. A 25 year contract for cable rights has to fail.
What happens when you can take a radio transmission or satellite feed, run it through a device, and have holograms enact games? Sounds strange, but we have Tupac shows now.
Regardless of delivery, the Nats have a contract with MASN to deliver the baseball content. If cable tv diappears, MASN will still own the rights to "broadcast" the Nats games, whatever emthod of delivery that means.
And more likely, it'll happen over time, the same way that it did for vinyl and CDs. For a while, some folks bought vinyl; others bough CDs. Then, there was a tipping point and vinyl got less popular, then less profitable, then extinct.
Baseball broadcasts will happen the same way, MASN will have games on Cable, FIOS and Satellite. Someone will propose a different "delivery" method and will license the content from MASN and there'll be an overlap in time of delivery methods. And then TV may get phased out over time...