That question has no answer. As AT&T have proven it can and does eventually happen again. The corporate profit motive is both infinite and inexorable. Not that it's evil or even undesireable, but the only effective counter to it is government regulation and protection. IMO these Title I/II protections have served our landline telephone network well for 80 years, or at least I can't remember the last time anyone was required to listen to a Geico commercial before dialing a telephone. Or mailing a package etc.The unfortunate thing here is its a self-inflicted monopoly. Why wouldn't it happen again.
IMO it's the best we can do to deal with the current monopoly. Far from a perfect solution imo but until somebody offers a viable third option it's the only one available.