To be fair, Roglic's prediction came at a camp in June. I'm pretty sure Vingegaard had been selected at that point.
I also think I've read various stuff stating that it's always been the long-term plan that Vingegaard should become Tour captain, it's just that "long-term" ended up being sooner than expected.
I feel that their Tour selection is sound. Personally i don't see such issue with van Aert going for green. As for two spots remaining. I would take additional climber in great shape or some member that is invaluable for good team dynamics and still does a rather good job at climbing. Too bad Martin retired as i would take him too. There should be someone to take some pressure off of Dennis. And the Tour won't disappoint. That is not all GT favorites will finish the race and if by any chance that would somehow happen there is no chance some team members won't take a hit. A role Dennis will have hence needs a backup. As for Vingegaard i would say he has a realistic chance to win the Tour. He will hence likely prove to be invaluable for the team.
P.S. Nice to see Dumoulin at the crime scene again. Should be well supported at Giro. If he performs good, no special reason i would believe otherwise. Then maybe some TTT at Vuelta will be at play.