I think what you’re getting at is technological stagnation (at least in terms of the utility users draw from protocols) but a succession of rolling waves of net

I think what you’re getting at is technological stagnation (at least in terms of the utility users draw from protocols) but a succession of rolling waves of network-effect-driven client adoption. And that’s the key point: if the user experience is essentially indifferent to underlying protocols what drives these waves is the relative ease of getting in contact with the group of people with whom you wish to converse. I don’t think Skype has been supplanted, it’s just been accosted... and, ironically, who drives this is not those who has several different applications on device suitable for connecting to different people who use different networks, but rather by those who insist on having a single application and that thereby force others to make decisions that suit them because they have a single option.