Hi,
we at Planeshift (www.planeshift.it) have created one of the first open source MMO in history (first release in 2002), based on Crystal Space engine. The game is still alive after 15+ years 
I’m now looking at moving all our code and content to Unreal Engine, and I will really appreciate some chat with you, as you seems to have good UE knowledge and MMO orientation. Will be great if you could connect to our IRC at irc.freenode.net in channel #planeshift . I’m there with name Talad.
For the UE port our licensing model is not defined yet, but I’m very inclined to keep it open source.
At the moment we ported all the server backend logic, including database connection, and loading in UE server of all our data (characters, items, npc dialogues, …), but we still miss a lot to have this visualized on the client.