The reason it feels finished is they were green lit for 5 seasons, part way through season 4 they were told no season 5 then after S4 they were green lit for season 5 again.
I had a peek at season 5, new captain and no ivanova. The new captain has some of the Ivanova attributes from what I can see in the first episode.
First impressions I don't think it's a huge loss, I found ivanova the least engaging of everyone, Marcus was an interesting foil for her as he was so engaging.