Corv has announced, in a comment here, that the Titans of Ether will be releasing the assets from Ultima IX: Redemption at some point in the future:

Info Update: I will release Redemptions complete landscape incl. all the custom models AND the story doc!

The unfinished featuers and quests will not be included because people would not understand what they have and complain. So I make it straight forward and simple: It’s all of Britannia and the models and the story, so everything anybody needs to create Redemption within a year if he/she wants to and does not try to, like we did, create custom features that Morrowind did not have.

So there’s that. Of course, in the same comments thread, Corv also made plain his frustrations with the Morrowind engine:

About the MW CS:

it isn’t an engine, it is a mod tool. The main difference is: it’s a tool to modify the game it came with, not a complete engine to create you own game. We pushed the modifications further than anyone with tricks, but that also has its limits. Problems we could not overcome:
– not possible to move objects in the world
– not possible to create our own combat system
– not possible to create our own magic system
– not possible to create a satisfying party system
I could go on and on.

This isnt’ just something “from a developers point of view”, this also impacts the gamer heavily in the end. Do you want a Morrwind with Ultima themes and hacked together features or a real cohesive Ultima-like game?

No doubt these concerns contributed mightily to the decision to both abandon Redemption as planned, and to abandon Morrowind for Unreal Engine 4.