Based on Kyronix referring to the 2015 Dev Diary
I revisited that and pulled out some highlights of what was discussed
"Time of Legends" Expansion
Draw on UO history
Shadow Guard and Valley of Elodon No idea on spelling here
I get the impression these are 2 new lands.
New loot/clothing/armor
male/female specific wearables Examples given were flowing dresses for women and new beard styles for men
2 new champion spawns
Currency conversions - Ability for any character on an account to access the loot from the entire account on that specific shard. (I'm guessing you won't need an expansion for that)
"Stone crafting" ability to change houses that are currently not customizable such as castles
Some sort of new Peerless type loot that enables the character to change his skill set? I got the impression it would be like a sword that gives you 100 swordsmanship or something? Not sure what that part was. It's a little vague so I'm not sure exactly what that's about. But it's something about changing your template without raising the skill cap etc. tied into Peerless type drops.
So if I'm able to customize my castle I suppose that would put me into a situation where I might want this expansion if that happens. Naturally I'd have to see what actually happens. I got the impression you would need to go to these new lands to get building materials for this project, but I might be off base with that. Anyway check out the video at the top and put it together for yourself