Edit: Changed file format to jpg.
Note that this thread does probably not include all upcoming items. The screenshots below are all collectibles with an ID of 1144 or greater. The collectibles right before 1144 are known dungeon trophies that already exist in the current live version, so I assumed all new Morrowind collectible would be added afterward.
There might be some not yet released collectibles with an ID less than 1144 though.
Let' start with my favorite. Nothing beats this piece of dwemer absurdity
Also watch out. Possible spoilers ahead as some collectibles are rewards for quests!
The following screenshots are slightly bugged. The collectibles displayed in the tooltips do not have a preview. Some because they are mementos/houses and some others because they are still in development.
The preview you see is a random other collectible and is not representative of the collectible shown in the tooltip!
@Thealteregoroman I don't know if you want to change the thread name to say this has all the items in?
That way others looking can come here and see.