In my personal opinion Remco can be the guy more close to vingegaard in the Tour, because he is the youngest of the four, and he is the one who has more room to improvement than pogacar and roglic.
Roglic is 34 years old, i find difficult to see him improving to a necessary level to beat vingegaard, that he never had.
Pogacar will go with the Giro in his legs and we already saw that vingegaard is a better GT rider than him.
The only one who has room to improve a lot is Remco because he's just 23 years old, and just like vingegaard, he started more later in profissional cycling. He can improve to a level that we never saw, and give at least some fight to vingegaard. There's a chance that it could happen or not, let's see, but it would make sense that Remco improves much more than the other opponents because of this factors.
Of course it can also happens some crash, some incident, he can fade again in the mountains, but theorically he has a room to a significative improvement.