* More companion comments. Not something we will see for a while at best, considering the amount of extra lines (8 stories times 1-5 companions times dialogue options) vs the visibility of the change, but the thing that makes me like on companion over another is precisely when they join the conversation now and again, to offer their views in a more direct manner than +15 affection. VA can chew through lines pretty quick, so I could see them retrofitting some of the older class quests with more chatter in an expansion, where they have to extend the personal story anyway and have most everyone in the booth already.
* The ability to invite someone to a guild by Legacy rather than character. Optional in case people want to multiguild, but for most you only ever have one guild, and it would be nice that you don't have to go through the invite hoop for every alt you make.
* Get rid of mob tagging. Wishful thinking probably, but if the engine and code allows it, I would really like them to take a leaf out of GW2s playbook and just give full XP + loot to all who help kill a mob even if not grouped. Competing for spawns or forced grouping with strangers does not build community, it just annoys and makes everything take longer.
* New Legacy unlock track: Increased XP from sidequests. Same as the one for Class quests, just for the other quests. Though I daresay with the arrival of XP boosters, this is also probably one of those we won't see.
* Animation timing tweaks. Especially noticeable playing a tank. The deflect/parry animation (which is nice and should stay in) tend to get in the way of trigger abilities with somewhat long animation (Force Scream on the warrior is where I see it most). Not sure if it is just a visual thing, or it actually delays my casting, but it makes stuff feel sluggish. Maybe just a priority tweak, such that active ability use animations superseed passive animations.