Could he mentally handle fighting on if Usyk brutally knocks him out, like he should have in the 9th round of their 1st fight?
Usyk came close the first time, but ultimately couldn't keep him down. It won't be likely the second time around imo. But if he does? Probably retires unless there is serious money involved. He's no spring chicken anymore.
Would announce retirement but would be back like other retired boxers had done before after contemplation. Likely such could also lead to Joshua-Fury faster or finally.
100%. Only big fight remaining for him is AJ, he gets knocked out by a smaller less powerful man, he's not risking it against AJ.
But he could of if not for the ref. I am not saying the ref did anything wrong--Usyk himself says he appreciates the man. But it is similar to the ref call in the Dubois-Usyk fight, in that even though it may have been a good call, not every ref would have made it. Also, though not exactly what OP is envisioning, Fury could get stopped on cuts from all the scar tissue.
Aj-Fury in Wembley will happen no matter what.. "Battle of the British Brittle " Probably for the one 5 versions of the WBA belt and the special belt created by Turki..
The ref correctly called a knockdown, and Usyk had three rounds to follow up on a clearly hurt Fury. Short of the ref letting Usyk hit a fallen over Fury how else was he getting the KO? In any case, we can only make judgement on what actually happened. Usyk landed his best shots, and like Wilder before him, he couldn't finish the job. A fight stoppage via reopening a historic cut isn't really the same as a KO either. I don't think Usyk would take much satisfaction in such a victory, and will opt for another points victory like he did against AJ.
Will Fury retire if he gets knocked out? No, because after some time he will feel as though he has nothing to lose and he'll seek the most lucrative matches.
And not every ref would have ruled Dubios v Usyk a low blow. It's not relevant speculating on what could have been, when the right calls were made already.
Another ref would have let Usyk hit him a few more times, even it stopping it was the right call. If that other ref is in there in two weeks, Fury may very well be stopped.
I always thought he would, especially around the Wilder matches. But he did take the Usyk loss surprisingly well and so maybe he wouldn't. As for the Usyk 'KO robbery', Usyk nailed him clean a number of times after that and still couldn't put him down. He definitely had his chance to at least KD Fury and get him wobbly enough on the get up to have the ref stop it. He failed to do so. Then ran out of time. The whole narrative there is warped like everything else about that fight. Obviously it might be stopped there in a small fight or domestic fight etc., but that's not what it was, it was the very opposite. Also, it was unlikely the ref would ever stop it without Fury at least going to the canvas, so it's normal Fury was allowed to wobble around a bit on his feet and Usyk would have been given the same chance. Meanwhile Wlad himself was dropped three times before being stopped against AJ (and that could have gone on), was also dropped three times against Sanders before the stoppage, and was given a KD for falling into the ropes against Brewster and allowed to end up like a dying ghost on the canvas before being waved off. Algieri was dropped over a handful of times against Pacroid. Briggs was beaten to death over 12 by Vitali and ended up in hospital. So people just have their different standards.