Heh, the last line of Dragon's Teeth:
Janeway "I think we'll be seeing them again."
I'm glad they didn't bring back the Vadwar. The idea for the Vadwar could have worked but it was poorly executed. It was the sort of thing that might have worked if the show was more serialized and we had already gotten some historical priming.
I think what would have been awesome is to see what happened to the Vidiians after the phage was cured. To see them pay the price for centuries of harvesting people's organs as they're trying to rebuild their once-Federation like society.