The difficult comparison here is that we have never seen any company monopolize so much of media as we have facebook and google do world wide. The only comparable example I see is possibly disney, and I wouldn't be surprised to see facebook and google succeeding far into the future due to well targeted acquisitions.

Additionally, it's important to remember that all of the largest american oil companies today are descendants of standard oil, and I imagine such could very well be likely if any of these other big monopolies were broken up today when it comes to the internet.