Coric is one of my biggest disappointments. In 2018 I was pretty confident he was gonna break into top-10 and remain there for a long time. He won Halle beating Federer (at the time world number #2) in final and had an amazing run in Shanghaï, (Wawrinka, Delpotro and Federer). The final was a great match despite the 63 64. His game looked a lot like Djokovic, his backhand and defense game were one of the bests. But it went downhill after this. Many unexpected losses, and now it's injuries after injuries. The US QF against Zverev last year was awful, one of the worst slam matches I've ever seen. Now I'm not even sure he will ever be top-20 again.
Norrie is a bit overrated here, I agree. He just doesn't have the game to beat top players. If he can't even beat the current injured versions of Nadal and Federer, he will never beat Medvedev, Zverev or Tsitsipas. His best results this year were in 250 and he didn't beat anybody ranked above him. He will be a solid top-30 maybe top-20 but no more. He isn't winning slams or Masters.
Same for Sonego. He rarely ends up winning vs top players. Djokovic in Vienna doesn't count for obvious reasons. Thiem was injured and not in form. His only significant win this year is Rublev in Rome. I don't see him winning Big Tournaments in the future. A 500 maybe.
Karatsev and Khachanov are another story. Khachanov has already won a Masters, and has an OG medal. Was in QF of RG and Wimbledon and I have no doubt he can do better even on hard courts. He has the serve and the power to trouble a lot of players when he is peaking. I can easily see him winning another Masters in the future and be in SF of a couple of slams. Why not win 1 one day, I wouldn't rule him out.
Karatsev is a bit of a mystery. He is 27 and I had basically never heard of him until AO this year. Wasn't even ranked top100 until late 2020. All of a sudden he beats Djokovic, Medvedev, Rublev, Auger, Dimitrov, Sinner, Schwartzman and many other top-30, wins a 500 and Semifinal in a slam. Now since RG he is back to the modest top100, practically unknown player he was all his career, losing to guys like Chardy, Bublik, Kohlschreiber,... Will he ever play his Dubaï level again? Hard to figure him out at this point...