At several points in the policy discussions at Freedom to Connect, it's struck me how little people understand the differences (business and regulatory) between the core of the Internet and the core of the PSTN. Yes, there are issues about connectivity (a.k.a. Internet access) in the first mile, but the US carriers are not on the verge of owning the Internet.
Unlike the PSTN, the backbone of the Internet is completely unregulated. Indeed, the Internet is global while regulation is local, national or (in the case of the EU) regional. And practically speaking, there is no government oversight of the business relationships between backbone service providers. There have been occasional attempts to apply anti-trust rules, but with hindsight, they have been largely irrelevant to the distribution of businesses that form the core of the Internet. In any event, no monopoly has emerged.
Data: Over the years, the Cook Report on Internet has covered Internet backbone issues and Internet peering arrangements. This issue from 2002 includes articles suggesting Internet peering is broken and other articles about how some Tier 2 ISPs have built donuts around the original Tier 1 ISPs - that is they have made peering agreements with other Tier 2 ISPs so as to minimize the amount of "transit" service they need to purchase from the Tier 1 ISPs.
Recently, Ben Worthen published a detailed map of Internet backbone connectivity in the US and follow on commentary. There are eight Tier One ISPs and many, many Tier 2 ISPs. I.e., in more than a decade - a decade that included both a boom and a bust but no regulation - there has been a proliferation of backbone ISPs, not a consolidation.
Is this stable? I don't know. But current US problems are strictly limited to the duopoly (or monopoly) in the first mile. No one (ISP or government) is on the verge of controlling the global Internet.