Its commonground for most mmos to phase out old content as time progresses merely because its not viable to constantly rely on older players to keep doing old contents the same way they once did theirs.

Its been done so far with the relic grind bringing players back to old dungeons and primal fights but how long will it last?

How long will it take before people get fed up with going back to Aurum vale or Garuda Hm for yet another quest/grind, 6 months....a year...2 years?

Sooner or later SE is going to have to find a way for new players to get help thru content whilst not making it as tedious as they were before, Garuda Hm beeing a example here since it has no ilvl desync and has become a viable means for the relic grind due to beeing fast and easy.