1)Destructible walls and pillars.Buildings too if possible.Since the game is using the new next gen CryEngine.Imagine,destructible walls that the player can use to their advantage to escape,knock out or kill enemies standing by the wall or dropping a pillar on guards from afar with explosive arrows by blasting a side of it's base.Or crushing down an entire floor on large number of enemies with enough firepower(like setting explosive traps around a building floor).It could be epic and more varied.But can also affect gameplay like destroying important artifacts that's part of a random side mission to be recovered which will result in mission failure.This can make players more thoughtful and reconsider their approach.
2)The feature to replay a mission with all current upgrades,powers and gear.Like in Hitman Blood Money where upgrades can be carried to previous missions.But there should be a feature to prevent players from cheating.
3)Add more missions,increase the scale and depth of each and every mission with more side quests like hidden rooms(similar to the one in High overseer Campbell's mission.),also adding clues in the form of poems or phrases in 'notes' and 'books' that hint of how to create runes(Granny rags recipe missions were remarkable) or bone charms.Missions should offer more choices when interacting with NPC.
4)More customizable gear-more blueprints,more upgrades and some extra varied weapons like different swords with varying stats so that each and every weapon is useful in their own way:Eg. An officer's sword has greater attack but lesser speed but an Assassin's sword has greater speed but lesser damage and weight,a choice for stealthy and swift players and another blade or sword that is every stat at medium not exceeding at every category but works properly in those fields.The mask optics upgrade was cool as it worked well when one would want to snipe targets with crossbow bolts-worked like a silenced sniper rifle.
5)An ingame feature to design our own custom assassinations with the option to built new maps with different buildings,tunnels,train cars,vehicles,ships,rail roads,mansions etc. and set our custom made objectives-which can be shaped online (also offline,by transferring files in removable drives for players who don't have internet.) that can york as a great replacement for multiplayer (the world offer to remember what made single player games so great.Every game doesn't require multiplayer as long as the single player is entertaining enough and has more than enough replay value.Developers should work on improving what they're best at rather than trying to do too many things at a time and not doing well in any of them.If it aint broke don't fix it.
LAST OF ALL AND MOST IMPORTANT OF THEM ALL.Let the next game have everything that was great about Dishonored.And that's everything.
Who wants to support me?