Imo, they did dethrone Sony. Xbox 1 was a better console than PS2, with better looking and better playing games.
Xbox 360 was also initially better than PS3. Cheaper, earlier, more games, better games.
Shame it all went to shit soon after that. Going from Halo Reach to Halo 4 was a disappointment, the first Halo I could not bear to finish. Japanese games dried up. They just lost sight of what was important, they though video games were utilities like excel and word and though "we have cornered the market with our software, our customers will stick to what they are used to". Sony and Nintendo were never going to let them have it so easily, they came back with everything they had, PS4 utterly humiliated Xbox: cheaper, more powerful, better games and no DRM bullshit.
MS 10 years later is still blaming the former CEO for that bad reveal in 2013. Guess what, Nintendo also fucked up with the WiiU, but nobody at Nintendo goes around crying "Its Iwata's fault we fucked up, what can we possibly do now". No, they fucking got to work and delivered good game after good game.
Still, there is hope, recently Spencer got his head unstuck out of his ass for a brief moment before getting rid of Tango Gameworks (Jesus, talk about incompetence) and saw it fit to work with Japanese publishers to release a game people actully are looking forward to, Ninja Gaiden 4. Maybe this is the beginning of a comeback? I hope so.