I'm a bit confused here. tigerfan said it would be easier for streaming services to add LOCALS. Your response implies a national feed and questions the loss of local commercials. Totally different animal. The better analogy is DISH and DTV wasting a ton of bandwidth to carry all the locals with much duplication.
Even a national feed with local commercial insertion is not going to be sufficient. You need to be able to insert local news/weather crawls and interrupts. Also pre-emptive programming. And given the fact that sports control EVERYTHING, you need to be able to deal with both blackouts and local coverage of major sports.
No, a national feed will simply not work, even with commercial insertion.