Yeah, it definitely made me raise my eyebrows a bit. I might be cautiously optimistic, though, because so many elements were just so good.
But as I am fond of pointing out, for the most part the ending is actually the same. All of our primary characters, both good and bad guys, are where they should be for the story to basically continue on. The Zack thing certainly presents itself as an opportunity to gunk up the whole works, but I think it's more than possible they've long since thought of how they want to make that work.
So, you know. Let's wait and see.