If I would make a poll now, I think I would keep Démare, Roglič, Pogačar, Evenepoel and Van der Poel. I would definitely flick Jakobsen and Ewan, probably also Groenewegen, Viviani and Van Aert. The latter is just too far away and is pushing 30 and doesn't do many small races, Viviani is close but is unlikely to win more than 1-2 races per season and Groenewegen just doesn't win much anymore.
Philipsen (45) is obviously the first replacement, then probably Pedersen (41) (although that would rely on him farming small races every February), Vingegaard (34) (I don't see it, he is too far away), Kooij (33) and De Lie (22).