For me this is always a very hard poll, because seeing a rider as a potential GT winner is not just simply a yes or no question, but rather a scale of likeliness that a riders wins a GT at some point. With that being said I decided to go for Ayuso and Rodriguez only.
Juan Ayuso (Prediction 70-90%)
Doesn't need a whole story around it I guess. If you can do this will in a GT at that age in your first year as a professional rider, than the expectancy should be that you win a Grand Tour at some point in your career. He will do it.
Carlos Rodriguez (Prediction 60-80%)
Bit if the same as Ayuso, but obviously a bit older. Has the same advantage as Ayuso that he is very likely to take the Vuelta seriously at a number of different occassions. So even if he doesn't reach the level of Pogacar, Vingegaard or Remco he should still be capable of winning a GT at some point in his career. Given how he is progressing and how little weaknesses he seems to have I wouldn't be surprised if he wins one at some point.
Thymen Arensman (Prediction 35-45%)
Maybe I rate his chances a bit too low, because before this year he definitely wouldn't have been on my list as I think he lacks a bit as a climber. However he has done tremendously well this Vuelta and I think he can grow further once he goes to a top tier team. Still he has developed quite a bit further, and it remains to be seen how often he will rider a Giro/Vuelta for the GC himself. Tour is obviously much harder too win, but with him being Dutch it is quite likely that he will race many a season going for the Tour GC if he reaches the necessary level for that.
Joao Almeida (Prediction 20-30%)
Rating him a bit lower than the guys before. Somehow I just don't feel like he will ever get the edge over all his comptitors in a GT. What speaks for him to a slight degree is that he will probably focus on the Giro and Vuelta quite a bit due to Pogacar. Whats speaks against him is that Ayuso is also there, who is already at the same level. For now it might happen if it all falls into place in for example next year's Giro, but I think Almeida might have less chances to win a GT then his current age would imply
Aleksandr Vlasov (Prediction 25-40%)
Dont know why but I rate him a bit higher than Almeida. On the days that it works for him Vlasov really is the winning type where Almeida usually still suffers, only to come back if the other favorites look at each other a bit too much. What speaks against Vlasov is that I see Bora lining him up for the Tour in the next couple of years. But should Vlasov do a Giro I could see him winning a GT fairly soon. But also for him I think he will just have the occasional chance.
Cian Uijtdebroekx (10-50%)
Very hard to rate for me currently. Very talented guy of course, but he could end anywhere between being a genuine GC contender everywhere he starts or riding for spots 6-10 in GTs in a couple of year. Just hasn't done enough WT races for me to do a bold prediction.
Other guys that I would mention at the moment is
Mathias Skjelmose Jensen, who is missing some climbing ability, but is pushing the watts in TTs and has very good overall racing skills in any other profile. If he manages to improve his longer efforts on climbs I can actually see him becoming a real GC contender in one week races first and actual GTs after. Also I will make a prediction by saying that
Emil Herzog will appear on this list in the next 3-4 years.
Other guys like Lopez, Landa, Gaudu etc. just lacking too many skills for me to see them winning a GT. Mas might do it, but I am gonna guess he will end without a GT win by the end of his career.