Rare mobs - my idea would be to have some rare mobs than roam the maps, they are hidden on the map until someone attacks or is attacked by set mob, once the mob is in combat then it would show on the map. Once the mob has been defeated you would then have to claim the loot (the same as when claiming any other objective) these rare mobs would have a decent loot table and say a chance at a super rare drop like and infusion, ascended chest or legendary mats)
Bounties - a system more for the 1v1’ers, roomers and small scale fighters. You can toggle it on and off (at the main spawn for each map) when turned on you will be randomly given a target (bounty) every day 30 seconds your bounty will ping on the map. However you will also be marked be another player. The higher the killstreaknthe bounty has the higher the reward (note there should be a system that would give you a target on a similar killstreak to you)
Warclaw - my thought would be to remove the Warclaw track, make it so you just have to do the collection and that’s it. Being a late starter to GW2 and having to run around in WvW without a mount nearly put me off the game mode. When everyone has a mount and your stuck on foot trying to keep up with the group is a real bummer, the collection was fine and fun. The reward track was just like putting salt in the wound.
These are just some ideas I thought of. Feel free to agree, disagree and discuss o/