Hmm... As far as gaming hardware goes, a pseudo-monopoly (70%-90% market share) does provide one huge advantage, economies of scale.
The true advantage that brings is not on the hardware side, but rather the software side (what consumers actually care about, games! ). Having a large market allows third-party developers to take more risks on a single version of a game and not have to worry about being exclusive to the wrong platform or having to spend more money to make ports to capture enough potential consumers.
A lot of the hardware psuedo-monopolies over the years, have had some extraordinary libraries of third-party games. Examples: GameBoy, GameBoy Color, GameBoy Advance, Nintendo Entertainment System, Playstation, Playstation 2
And because it is not an absolute monopoly, the hardware prices have to stay at a (somewhat) reasonable level otherwise sales market-share will shift to another competitor.
I see this as the best outcome for consumers (i.e. gamers) as it minimizes our costs and maximizes our choices (as in less rehashes, sequels, and ports; more innovation, new IPs, and experimentation in games).
Just imagine how much more interesting this generation's library of thrid-party games would be, if one of the platforms had currently sold 140+ million consoles.










