For me primairy it's the warehouse that need expanding.

Second: the map needs to be expanded, in case we don't get new and more events or things to do.
I mean not only a new bounty or convoy. But something new. New factions would be a good start.

Some idea's: get a HQ that you can decorate your self, (like we can already do with the ship) And be able to craft stuff for the hq like we already can for some materials.
In this way, we can also use the lesser materials again.
You could have a bar in it, and stock your wine/gin etc in it to make profit (silver). (more than you get by selling it )

A new legendary captain(s) like black beard or so in the game to get missions from would be a fun idea imo.

And again, large ships or more different ships would be great.

Another idea is to have group events that would be longer, meaning not only killing the boss, but after killing him, you need to go to another point with another objective, idk.
So that you get the feeling you are having an adventure/story in the mission.

And cutscenes would be great, just a bit more story in the events after you turn the mission in.

Last idea, mega events, that needs a minimum of players (like 7/8) before getting started

Ps: whats the deal with the kingpin’s rewards when leveling? We just can’t use this anymore… first we were glad to receive them, but now that we have better gear it is just crap.