If by that you mean game servers on player owned servers, they would benefit most of the updates on the server side as they will share a lot of the code. And they should be quite moddable but will be limited by engine side to some degree. Unfortunately I am not familiar enough to tell to what degree it will be limited.
Unfortunately I wouldn't know it until it is decided. The issue with servers on OCE is that our main provider doesn't provide servers close enough so we had to rent servers from another provider. Our server infrastructure allows increasing number of servers by demand so we can always have a server ready for players but we cannot currently do that on OCE servers since the same tools are not available. If we wanted to allow matchmaking on those servers, it would get quite slow on peak times. I don't know what is the plan regarding that, I am sorry.
Edit: Seeing some comments I wanted to clarify something. There are different teams working on different parts of the game, it is not a one big MP team. So one team, like mine, working on social stuff and lobby server related stuff doesn't mean that these features have higher priority.