At this point the eternal realm gets everything from activities, quest, new gear and the only thing left is the season pass comestics, by which is the only reason i will play it since i got plat left and as soon i got all i will return to eternal realm.
This said there is no point on even try to reach 100 on seasonal or grind since i’ve on eternal each class at 100, glyphs all maxed, nearly all uniques and a couple ubers ready to use.
TLDR: Eternal Realm is now VIABLE and not missing content previously “seasonal only” aka activities.