Such a thing is impossible to predict but anyone who believes a company or business cannot crash hard needs to go back and look at history. The prerequisite, however, is someone coming up with something better. That means a timeframe is nothing but a guess, especially since the companies in question might be the ones to come up with that "something better"--or, especially in Microsoft's case, the company that buys the company that comes up with something better.
As far as the underhanded way these companies do business, I don't think that can really be argued. They get away with it because they can. When you control the market, you can dictate terms to consumers.
Microsoft is a good example of this in both directions. They control the OS market so they do what they want while basically ignoring any backlash. They tried to do the same thing with the game console market but lacked the same kind of leverage and got knocked down a peg.
