Not going to happen. A new Xbox in the middle of PS4's reign could fare even worse than X1 (same poor sales outside of US, but weaker sales in US due to cheap, game-filled and popular PS4) and truly nail the brand's coffin. They have to bear with this gen, "tough it out" until the next one.

Thore are the most probable years.

That would be an awful idea. MS would gain nothing from doing that.

Not even close.

XB1 has sold 3.5 million more (aligned sales) than X360 so far.
http://www.vgchartz.com/article/263022/xbox-one-vs-xbox-360vgchartz-gap-chartsdecember-2015-update/

PC isn't really going to hurt. People who want an Xbox one will get one regardless. Its evident that for now, not many people are interested in it compared to the PS4.

Its also evident that lack of true exclusives doesn't really matter. Sony knew this, which is why 99/9% of the reason to own a PS4 is ''superior'' multiplatform games.

Its simply a win win for gamers.

2018 and it will run windows.

I voted 2016.

They never owned anything.  360 was successful because PS3 was executed horribly, over promised, under delivered, was too complicated to program, and cost too much.  I'm still remembering the promise of 4 x 1080p HDMI outputs from the PS3 lmao.   

Sony did absolutely everything wrong and MS really didn't have to do anything but simply be there, like a rebound after a breakup.  And it came at a time when console hardware was finally in the realm of PC power at launch and console FPS was then a brand new phenomenon to console gamers and everybody (well, just the console kids that never had a PC) wanted PC style western shooters.  MS was just at the right place at the right time with 360.  Not so much anymore.  

These once in a lifetime favorable conditions aren't ever going to repeat again, and MS has proven incapable of diversifying away from their Halo/Gears/Forza/NFL target audience in order to adapt to non-favorable conditions. 

And this doesn’t even scratch on the DRM launch fiasco, ad burdened interfaces, and what was essentially pushing complete home integration to monetize your life (Kinect to count heads to charge for pay per view patent anyone?)  MS deviated away from the video game console market a long time ago.

This generation may also have big money "AAA" shooter fatigue setting in FINALLY.  Gears and Halo aren't fresh and exiting anymore.  They can't just throw Halo 6, Forza 7, and Gears 4 around and expect it to stick anymore.  Their one trick pony now a tired dead horse, and their platform objectively weaker this time around, they are just going to have to deal with it.

That said I'm not sure what's wrong with XBox One sales.  They could sell 900 million Xbox Ones and it would be labeled a failure if another platform sold 1 billion.  It's Call of Duty syndrome all over again, where anything else that doesn't sell a bajillion copies day one is a catastrophic failure, doesn't matter that some of the most beloved and successful games of all time sold less than 1 million units lifetime.  It's the same thing as businesses always expecting record breaking profits.  You can't break records every single year nonstop. Eventually the bubble pops.  Just because you didn't beat last year doesn’t mean you're a failure.

You can always find some other product that outsold yours.  Doesn't mean you aren't successful.

The Xbox 10 is a win/win for everyone as sometime soon Windows 10 Xbox store is going to open fully and be a rival steam service for PC and when they next console is built around this and fully integrated together there will be so much of a library to offer, and for the part that is lacking most on the Xbox One Japanese developers are porting more and more what used to be only on PS to PC, Yup next gen you will get Tales of, Neptunia, every Final Fantasy and JRPG along other Japanese games on the Xbox 10, The future will be strong for Xbox when it all comes together.

On the launch I still think 2018 is most the likely but 2019 at the very latest.