I would think at some point in the near future more games will also be streamed over the broadcasting network's corresponding website. Since the network themselves are streaming they still control the ads and can use stats showing number of people watching online to the companies that bought ad time, which means they are not cannibalizing their own ad revenue.
You could start with all playoff games, sunday night and monday night games (assuming they're sold out, to comply with the archaic blackout rules.) Further down the road you could have streaming sites look at your IP address and determine which sunday afternoon games are available to you. The only party that I can see objecting would be the local television stations, as the ads that they are allowed to run would not be visible to those watching online. Perhaps at some point those local-specific ads could seamlessly be incorporated into the stream at the appropriate times based on that IP address.
