List of things that will happen about the same time we see a long-term one-console market: Cubs win the world series; Israel and Palestine make nice, hug, and work things out peacefully; Rule 34 comes to an end.
The only way we'll get to a one-console future is if the governments of the world all fall and the new One World Order dictates a single console, or if two drop out of the market and leave only one standing. And even if two drop out, what is there to stand in the way of a new competitor jumping in and making it a two-console market again?
Sony already almost teamed up with Nintendo and got burned, which is why they're in the market in the first place. Both Sony and Microsoft have different visions for their consoles than Nintendo has for theirs - Sony and Microsoft view their consoles as means to an end of taking over home entertainment, Nintendo is a game company that's focused on machines without a great deal of unnecessary features. Then you have Microsoft's expensive Xbox Live vs. the largely free Nintendo system and whatever Sony's got going for them. And that's just a start of what problems you'd have to get past.
The idea of all three coming to an agreement on a single console that works for all three is a pipe dream, nothing more. And even if they could work out the differences, the one-console market would only work until a fourth party decided they wanted to get in on the competition and introduce a second console, at which point you'd be back to square one.
Like oldtaku said, the Sega and Nintendo comparison is a very poor analogy. Sega was out of the console market and downgraded to a 3rd party company for years before they made a game that combined their respective mascots. Wouldn't have happened if Sega was still making consoles in addition to games.
The only way we'll get to a one-console future is if the governments of the world all fall and the new One World Order dictates a single console, or if two drop out of the market and leave only one standing. And even if two drop out, what is there to stand in the way of a new competitor jumping in and making it a two-console market again?
Sony already almost teamed up with Nintendo and got burned, which is why they're in the market in the first place. Both Sony and Microsoft have different visions for their consoles than Nintendo has for theirs - Sony and Microsoft view their consoles as means to an end of taking over home entertainment, Nintendo is a game company that's focused on machines without a great deal of unnecessary features. Then you have Microsoft's expensive Xbox Live vs. the largely free Nintendo system and whatever Sony's got going for them. And that's just a start of what problems you'd have to get past.
The idea of all three coming to an agreement on a single console that works for all three is a pipe dream, nothing more. And even if they could work out the differences, the one-console market would only work until a fourth party decided they wanted to get in on the competition and introduce a second console, at which point you'd be back to square one.
Like oldtaku said, the Sega and Nintendo comparison is a very poor analogy. Sega was out of the console market and downgraded to a 3rd party company for years before they made a game that combined their respective mascots. Wouldn't have happened if Sega was still making consoles in addition to games.