Evenepoel. I can apply pretty the same as Pogacar. Plus I'm not really sure that even Vuelta Evenepoel can compete with top Pog. However, he seems keen to go for the Giro and if he doubles with Vuelta, he may very well have 3 by this time next year.
Vingegaard. He kinda reminds me of Froome. Even updated version of him, as he used to struggle bad in the last part of the GT's. If he goes to the Giro, he is my main favorite. This route really suits him to the toe imo. It's hard to design a better route for him, actually. He may very well win a few GT's, the main concern is that the others are all younger than him.
As a conclusion, I don't think we'll see riders having so many GT wins in future...And with the quantity of young talents emerging at younger age, many riders will be on the way down by the age of 28.
As to your last statement, I'd say it depends on whether or not a difinitive, epoch-making rider emerges over the next years. Until this year that seemed to be TP, but then Vingo beat him at the Tour (although I'm sure Tadej will be back with a vengeance next year) and then Evenepoel proved he is GT material at the Vuelta. Whereas the issue over longevity I think depends on who comes along, in say 5 or 6 years, capable of exacting the necessary pressure to bear and unseat the Bigs of today. One thing to consider, however, is that in cycling it is said a truly prodigous talent is born only once "every thirty years." I realize this isn't science, but I've heard more than one top pro say it in the past and about a certain current rider. The point is that if there is any truth to the assumption, in theory we could see a rider dominate for a decade or so and, in this case, arrive at 7+ GTs won (although, even if not a current, but recent, rider, Contador on the road sets a higher benchmark at 9).
And this brings me to the other two riders, Vingegaard and Evenepoel, the only ones besides Pogacar at present who seem possible candidates to win the title of this inquiry. One thing going in Jonas's favor is that, especially over the last decades, multiple GT winners have a dominant team to unwaveringly support their leader's ambitions. It was this way with US Postal/Discovery and then Sky/Ineos, but now that mantel seems to be firmly donned by Jumbo-Visma. Consequently, Vingegaard is on the right team to win the coveted prize and has shown at the Tour that he is arguably the best climber in the world at the moment, who can also TT rather well, at least when he needs to in a GT. As others have wondered, however, is he mentally tough enough to handle the pressure, expectations and fame of riding on the best team in the world year in and year out and repeatedly winning the Tour? Based on how he reacted to the whole post-Tour mediatic mayhem and the consequences for his private life, which he seems to jealously safegaurd, I have my doubts. In other words, Jonas seems subject to traumatic mental disomfort from this, if not to say psychological crisis (although he denys it, but would he openly admit to such a difficulty in his position?). By contrast, his main rival Pogacar appears not phased in the least by such overwhelming fuss and attention. Mental instability could thus be Vingo's Achille's Heal, but only time will tell of course.
Regarding Evenepoel I think it's fair to say he's finally back on track after his terrible and potentially life-threatening Lombardia crash with its very serious injuries, which for all intents and purposes gave a false impression of his actual level comming into 2022, because of a troubled and ill-fated 2021 campaign. That's because his recovery was handled poorly by the team. Principally the botched effort at that Giro he should never have started, negatively conditioned his whole season right down to the Olympics and Belgium's Worlds debacle. Now, however, we have seen what a healthy and untroubled Remco is capable of doing, as if the remarkable promise he showed before Lombardia 2020 is the trajectory we can expect for the future. Valverde's sensational assessment of his talent (he is "by far" the best), however one considers the matter, was an uncompromising belief in this. But again, only time will tell.
Perhaps the main obstacle in Evenepoel's path to GT dominance is his team, because it doesn't seem equiped in the near future to be able to control three weeks at the Tour, unlike Jumbo-Visma has masterfully done (also considering Ronan's praise of the squad, its methodology and rigor) or, until recently, Sky/Ineos. Yet Remco hasn't even ridden the Tour, so it's anyone's guess if he can handle the likes of a top Vingegaard or Pogacar on the big cols of France in July. On the other hand, who could argue the potential and talent are lacking after this season? Mentally he seems just as iron-willed and ferocious an assassin as Pogacar when wanting to stamp his authority over a race. His crushing dominance at Liege, San Sebastian and Worlds, moreover, arguably surpasses anything we have seen in similarly prestigious one day races from the Slovenian. This is why, in addition to his dominance at the Vuelta, I think Valverde was so struck by his athletic prowess. With this as a promise and if he continues to go faster up mountains and in TTs, then he's going to be a hard nut to crack imo even for the great Vingegaard and Pogacar (although perhaps Jonas's performance level on the Granon could only be matched).
On another note, he does seem to be a really emotional rider, as his outpouring of tears upon winning Lombardia, the Vuelta and I think Worlds too attests. Aparently this indicates an uncontrollable release of tremendous pressure that was bottled up within, a liberation of (perhaps good agonistic) stress and pent up excitement that must be controlled during the race to react lucidly and do the right moves. I attribute this likely in part, on the one hand, to a character trait of his personality. It isn't necessarily a flaw or weakness that could hamper him, however, as long as his emotions are transformed into positive energy (one thing that's truly remarkable about Pogacar is that he doesn't seem to know what pressure or stress means and simply treats even the most important races in cycling as play, as something just to have fun with/doing). On the other hand, being Belgian, part of Evenepoel's emotional outbursts after winning his truly big goals seem attributable to the overbearing scrutiny, pressure and expectation that's placed on his shoulders. Neither Vingegaard nor Pogacar have anything remotely similar to deal with from their national press or fans. The type of emotions this engenders within Remco could potentially cause problems if turned into negative energy, a prospect he and his team seem all too aware of, for which Andora has been chosen as the new geografical base, far from the intrusive atmosphere of Flanders. Yet while he seems susceptible to rage over critics and doubters, he evidently can harness that ire,
transforming it into an invincible force, which, once unleashed, literally annihilates the peleton like at Liege and Worlds.
Lastly, as regards the others you mentioned, I don't at the moment see a threat to any of the above three for the title among them. Some because they just don't have the talent, like Almeida and Hindley, others like Bernal due to injury (and perhaps he is not overall as capable) or Roglic, because too old, as you say; whereas specimens like Rodriguez and Arensman simply need to accomplish a lot more to be seriously considered. Ayuso, however, is an interesting prospect. But he still needs to step up considerably (in the sense that going from third to the top spot on a GC podium is a massive step) in both climbing and TTing and in this the others are still far ahead. True, youth is on his side, but it's not like the others are Methuselahs. His greatest hindrance, however, is that the Pogi is on his team, for which it will be years if he remains on UAE before Ayuso can assume top leadership for GCs. Thus unless he wants to target exclusively the Vuelta, broader GT ambitions and support at the Tour and Giro, doubtless necessary to coming out on top of this competition, will probably have to be on another team.