You can change, remove and add a feature/event/anything. But you do need to justify your answer to some extent. Go.

Change: Raids into a single instance. At the moment it does not feel like we're 'raiding' a place, more just.....being warped into a dislocated zone.

Remove: Diadem. It's horrible. A prime example as to why SE needs to have test servers, nothing about this worked. It was an interesting idea but lacked.....everything? Yoshi already demonstrated he could create a balanced synergy between DoWM/DoH in battle with Hamlet 1.0, so not sure what happened here.

Add: Dynamis. Borrowed from from XI. It'd be neat having an event set during the 1.0 invasion of the cities (Those that were not present: Ul'dah was a hot mess. And it was fun AF.). XI was interesting because you need sleep certain mobs, focus others etc etc. It'd bring CC into XIV in a meaningful way, and it's kinda fun beating up everything ever. Also would be a nice throwback to have Dynamis currency.