Some things I would like see in the next Expansion or next Big update.
1. Housing and furniture. To have an instance where we can invite people and decorate our home(similar to ff14). Able to craft some of the furniture will bring new life to the crafting professions and open a big market for them with all the customisation. I am sure Arenanet can monetise a large part of it with even more skins, so it is win win situation.
2. Guild incentive for.....guild wars. I know this is mentioned often, but still waiting to see a system where we can join guild and do WvW together regardless of server. Guild mission not only for capping objectives in WvW, but focusing on hunting and battling other guilds with some leader board for the top guilds and bonus points rewards when challenging them. As we had small updates trough the years it is finally time to see something bigger here.
3. Some Graphics upgrade will be nice as the game as it starting to show its' age. Especially as the whole driven factor for this game is fashion and tons of cosmetic from the cash shop it is needed to be on par with the times.