While they won't have hordes of materials like us, it should mostly be end game materials they'll struggle with. The problem with my theory is, I'm looking at how I had to catch up when I came back for Forsaken. Playing through CoO and Warmind helped, because I picked up materials during what could be considered a passive grind as I went through the stories. Do players still need to do that content or is it straight to Shadowkeep? If it's straight to Shadowkeep they could technically stock up on mats through Spider, because they will get glimmer just by playing and be able to purchase some mats from Spider. It's not ideal, but it gives new players an option.