Who said they would just sit on it? Why not make the Internet
now "The Internet, Brought To You By Company X?" You need Company
X's address space, so you have to provide Company X's services on
Company X's operating system?
This is exactly the biggest problem. It's naive to imagine that this
wouldn't happen to some extent. In the real world, there are a number of
Company X's who don't play nice.
It's this kind of thing that keeps areas of the radio spectrum
licensed by the government.
Although radio spectrum is more divisible than we used to think.