Think of the undersea cable network as the new economic trade routes and the commodity in transit as data — arguably the most important commodity of the Information Age. Amazon, Microsoft and Google own close to 65% market share in cloud data storage. This makes them major exporters and importers of data. Imagine them forming an oligopoly to own the routes used to transfer any data. Of course, end consumers would benefit from reduced prices that are passed on by the content providers, who now enjoy large economies of scale from owning cables. But smaller companies looking to compete will be at a disadvantage. They, or anyone else looking to use these cables, could be charged a higher price for bandwidth. This is no different from an oil cartel in some aspects. A worse, but less likely, privacy related concern is if Facebook decides to use all data passing through their cable to ‘improve their services’, regardless of who owns the data.
There’s a sea change underway in under-sea cables, and it seems to mostly pass by unnoticed, but it could have major consequences for the future of the internet.
I think you have this backwards, this is a response to Amazon, Microsoft and Google being raped by transit pricing and monopoly ISPs charging access fees. If the IP delivery market was competitive I don’t think any of these companies would own cables. You can only charge someone 100x the cost of providing the service for a little while until they decide to forward integrate. Do note that Internet service is sold with margins exceeding 95% profit in the US. Why pay that kind of price when you can lay your own cable?