Joshua is a not a bum so he wouldn't take a beating Sizzora or Wilder took off Fury and even if he did, he'd take it a hell of a lot better than Wilder. And imagine being mentally brittle and winning Olympic gold in your own country, getting of the deck fighting and winning in front of 90,000m in the national stadium against the best Heavyweight of the previous decade, and coming back after your only defeat, taking the rematch straight away, rebuilding and winning on points Any other man would go on a drink and drug binge blow up to twice the size and spend 3 years on the sidelined citing mental health issues.
If this fight ever actually happens before they're both 40 Fury will not be going on the attack like he did Wilder, Joshua despite being a roided up bodybuilder still has a bit more skill than Wilder and is just a more powerful bloke in general. Fury won't beat him punch for punch, he'll be going for a points win. Possibly Joshua will gas of course, I think they'll both be cautious which means Fury on points.