A journey of 1,000 miles begins with a single step.
This itself if marginal, as most viewers already have access to NBC over the air. Getting a package like MLB has would be tricky, as they have contracts with Fox, CBS, NBC and ESPN. They could, I suppose, stream the NFL Network or let people watch older games on demand.
Sports is one big reason that people keep their cable TV. We are seeing more and more sports being available via the web. Early in 2008, I was debating someone who insisted that we would never get our TV via the Internet. He kept insisting on this even though I was able to go to content provider's websites and watch episodes. And then along came this Roku box which really changed a lot.