What I'd like to know why do you think MS not fucking up will take the lead from Sony exactly? Are you expecting Sony to fuck up next gen? Last gen with a crippled Sony it was a tie, there is really nothing pointing out that MS can compete with Sony WW.
Sony wasn't all that 'crippled' last gen. The only mistake they made was with the overengineered hardware and resulting launch price, but at least it was somewhat justified with the additional power and Blu-ray player, whereas XBO's really wasn't justified with a significantly less powerful console and a bundled accessory nobody wanted.
Outside of the launch price - which was later resolved by removing BC and then the Slim - they weren't crippled at all. Sony had a strong and diverse first party output last gen from God of War 3 to Uncharted trilogy to Resistance trilogy etc.
And meanwhile on the other side, Microsoft had to deal with RROD - the biggest console hardware disaster of all time.
Xbox 360 didn't sell ~85m units last gen because Sony was somehow "crippled", or indeed doing anything wrong, it was because Microsoft had a compelling offering. Just as people aren't only buying Switches and PS4's just because XBO has been weak this gen, they're buying them for their respective offerings.
I think we have to get away from winners and losers, and realise that if Microsoft provides a compelling offering again next gen, as they did with the 360, then people will buy it and it can compete with Sony and Nintendo's offerings. That doesn't mean it has to outsell them, but it will inevitably do significantly better than the ~40-50m that XBO will end up selling by the end of the gen, which will be a success for Microsoft in its own right. Burger King isn't shutting down all its operations just because McDonald's sells more burgers.