A hypothetical board meeting back in 1983:
Suit 1: Within three years, IBM will be fighting to keep above 60% market share.
Suit 2: If I had a nickel for every time I've heard that...
Times change. I'm not saying that the poster is right, but there is no empire that does not fade and no monopoly that does not go extinct. 'Tis the way of the world.
Only when something better comes along, that is easily available to everyone who wants it. And right now there is nothing on the landscape that jointly meets those two requirements.