360 was never "killing" PS3 in sales. The reason it had a few million lead for so long was due to launching one year earlier. Other than that their sales were always quite close.
Compare that to the current situation where PS4 is outselling One by at least 3:1
No, the reason the PS3 took so long to come back to life wasn't the year head start. That is revisionist history (and incorrectly used in arguments daily). It was the launch of the slim model, price cut, rebranding (change to PS2 font etc.) and an awesome Kevin Butler campaign. After that, sales went through the roof and never stopped. Go on, look at the data. Here is an article talking about the woes of the console before it even launched and how the slim was hoping to turn it all around.
So basically Sony taught us that you're never dead as long as you've got great marketing guys working for you. I'm not saying MS has them, or will hire them, but the fact that it's been done should temper some of the bravado imo.