Again, not the same circumstance. The PS3 had the entire world to back it up and push it ahead and it cost Sony billions. MS neither has the first party that Sony does, nor do they have the whole world. If they loose NA, they're pretty much done (and even Parity means a massive shrink in their install base).
The PS3 also had the advantage of coming off of the absolutely massive PS2. The X1 is coming off of the very successful, but nowhere even remotely near the PS2 360 (which is why I'm baffled at MS' arrogance, at least Sony had some reason).
From a sales point, this gen is pretty much decided (WW at least). Of course, there could always be some extreme events that change things. Like, MS could decide to hand out consoles for free, but that isn't going to happen. The gap is already around 3 million, it'll continue to grow for the rest of this gen.
The X1 will be lucky to do half what the 360 did, but at the very least it's in a much better position than the Wii U, which isn't really doing well anywhere.