2/3 of the 99 Blues team couldn’t make this current team.
I assume you're talking about the 1999/2000 team since that team was the one being discussed. I also assume you mean "the player at his skill level at that point in his career" and not those players a decade+ later once their skills had declined.
Pronger, Mac, Demitra, and Turgeon are all insanely clear locks to earn roster spots on this current team.
Handzus had 53 points that year as a 22 year old and finished 2nd in Selke voting. He absolutely would have a spot on the current team.
Young "only" had 39 points that year, but that total was sandwiched between 52 and 73 point campaigns. He was a good defensive player who was in the midst of an 11 season streak of scoring 30+ points. He absolutely would have a spot on the current team.
Hecht had 34 points in 63 games as a 22 year old rookie and went on to score 463 points in 833 NHL games. He'd absolutely beat out guys like Mac, Barby, Steen, Blais, and Kyrou.
Same with Conroy. In a down year, he posted 27 points after 2 seasons of posting 39 and 43 points while being top 5 in Selke voting. We traded him the next year since he became expendable and he went on to post 75, 59, and 47 point seasons in Calgary while helping them to a Cup Final. He absolutely beats out a number of guys to make the roster on this year's team.
Richer had 25 points in 36 games with the Blues. He had 33 points in 64 games the year before. He would be an upgrade over a number of our depth guys.
I really don't see a reasonable argument that those 9 guys aren't clear upgrades over at least a handful of guys on the current team. That's already over a third of the roster before you start talking about guys like Pellerin, Mayers and Nash who were very successful in depth roles and make compelling arguments to bump out current players in similar roles.
I agree with your sentiment that the current Blues team is the deepest one we've ever had. We don't have a guy as dominant as Pronger, but this is one of the deepest teams I've ever seen (league wide). But that doesn't mean that all of the bottom 6 guys couldn't be upgraded with legit middle 6 (or even top 6) caliber players. Building the depth we have in a cap league is remarkable, but you are selling the 1999/2000 roster incredibly short by claiming that no more than 7 of them could crack this current team. That was a hell of a roster who set a league record for fewest goals allowed in an 80+ game season despite the entire hockey world knowing that their weakness was goaltending. That team was absolutely loaded with incredibly good two way forwards who would thrive in the middle/bottom 6 of a Berube-style team.