I'm not an expert, but I think what you describe is exactly what happened with telephone service in the United States (i.e, the breakup of Ma Bell, etc.)
It wasn't the breakup of Ma Bell, but the telecommunications deregulation bill of the mid '1990s did include a provision that required local phone service operators to sell access to their network to newcomers at wholesale prices.
Unfortunately, cable companies live under a different set of regulations, so the same rules don't apply to them. Meanwhile the industry progressed to the point that in many markets companies that were once just cable and phone companies now offer the same menu of services. But the law hasn't changed to keep up with that, so the net result is that we've got a regulatory regime that cripples an already anemic competitive environment by arbitrarily giving an enormous advantage to only one of the players.
Unfortunately, cable companies live under a different set of regulations, so the same rules don't apply to them. Meanwhile the industry progressed to the point that in many markets companies that were once just cable and phone companies now offer the same menu of services. But the law hasn't changed to keep up with that, so the net result is that we've got a regulatory regime that cripples an already anemic competitive environment by arbitrarily giving an enormous advantage to only one of the players.