Personally, I thought the developers would continue with the fifth game. There are some unresolved issues in the storyline. For example, what happened to Railagh? He went to search for the Skull, but in Dark Messiah, there's no mention of him at all.
But in general, if we don't take the storyline into account, the developers really put in a lot of effort when creating the latest expansion. I don't even know what else could be added.
P.S.
They will be so bad that no one will want to play them.