Will probably not be very popular given the number of times people have cried over not being able to clear duties that involve performing game mechanics but...

An MSQ containing numerous solo duties that require the player to successfully complete mechanics to clear that will take players through every battle mechanic introduced so far in game. Solo duties that are super easy if you do the mechanics correctly and nearly impossible if you don't. That way even the people that skip potion their way to jumping straight into Endwalker will still have some experience with battle mechanics by the time they'd gotten into endgame. Some people will complain that it's gating content, however I see as no different than requiring player's to improve their skill. It's no different IMO than a single player offline games that become more difficult as you reach later stages in the game.