I for 1 hope to see the introduction of red items, which are super rare, have max bonuses only, but no upgrades on them yet, because u need to buy those yourself, this makes it more interesting to salvage weaponmods like lengthens deep wound, etc. It would also make maximum stats weaponmods more valuable.
When u customize them at a weaponssmith, u get a menu where u can choose a name for the weapon.
(would be nice if you can only choose weaponnames which havent been used before, else you get 10 air spikers with "stormbringers")
When you doubleclick on your red weapon in your weapon slot, holding the control button, u get to see

I also hope to see a new guild battle mode in which you need to defend your guild hall against hordes of monsters, which only drop small amounts of gold, and the more "horde battles" you win, the more guild points you get.
These guild points are needed to repair your guild halls walls(I'm just making suggestions) or you can invest them in new rooms, furniture, or npc's in your guild hall.
Yes, i also hope to see the inside of a guild hall, since it's kinda dull having a real cool guild island, and having to sleep outside

Well, thats all suggestions i have for nightfall, I know I'm looking forward to it, and i can't wait to get my hands on the controllable henchmen which guild wars has anounced as 1 of the new features in nightfall.
Post any suggestions, how dumb they might sound, because I'm sure the guild wars staff needs plenty of new idea's for upcomming chapter's.