Keep in mind that he's talking about things like wired fight sticks, and not the wireless controllers. Most people probably prefer wireless controllers for most games, but fighter enthusiasts prefer arcade/fight sticks, and a good one is three to four times more expensive than standard controllers.
On that note, I haven't seen anything about wired controller compatibility. However, given the controllers have the same number of buttons (Start and Select have been changed though), it's plausible.
Ok I see what you mean. Who knows, but I'd say probably not. If you were a developer of a fight stick for the 360, and the Xbox One came out, and you wanted more money, you'd ask Microsoft to not make them compatible so people have to go and buy the EXACT same thing again. Wouldn't be surprise but that's me speculating. We'll see, don't be surprised though.
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Lets not talk about speculation though. I'm VERY excited for the new Xbox integrating into TV. Maybe some people are not, but I'm hoping this brings some really cool things especially with the NFL. Imagine watching a game and being able to say "Stats, Tom Brady", or whoever your favorite player is and seeing their stats come up in a sub menu for the game.
Or playing a video game and saying "Launch Internet Explorer(Wish we could say google chrome haha)" and go see the strategy guide you have up on the side.
Microsoft went EXACTLY for the market they always said they would. They wanted to be the centerpiece of the living room. They tried with WMC, the HTPC, and now this all culminates in the Xbox One. I don't think the gaming experience will be too noticeable between the PS4 and the Xbox One. (speculation I know sorry) I don't think that they're going to make textures for the PS4, and then AGAIN for the Xbox One. They'll make textures that both consoles can handle. We're competing on features at this point, and I think Microsoft, being a company 10 times the size of Sony, has the pull with cable providers, sports (NFL, NBA, NHL, etc.) to bring content to the new Xbox that pushes it well beyond what Sony is capable of as a company, not as hardware, to bring to the plate.
While a lot of guys here classify themselves as "Gamers", I think Microsoft will pull the market of people who "want to play games" and don't consider themselves to be "Gamers". Xbox One hits a lot of spots that both the Wii and the PS4 just don't have the clout to hit.