Probably a dumb question, but slightly hard to search for an answer. How do other games handle this? Currently a level 50 with item level 90 gear is substantially stronger than a level 50 with item level 50 gear.

If a new storyline is released (likely in an expansion) or the level cap is raised, SE will clearly make a level 50 with item level 50 gear able to progress in the main story (SE won't punish players who are casual and don't participate in grinds / endgame). However, veteran players aren't going to want the main story to be a cake walk. How is this resolved?

Imagine a level 51 main story battle. Does SE cap the item level to 51? Or is a level 51 weapon / armor more powerful than a level 50 item level 90 gear. If the latter is the case, the stat difference between your storyline level 50 gear and your level 51 gear would be absurd.

Any thoughts or previous MMO wisdom?