Gasser will be on the 60-day, so we won't need to count him. Ashby is under contract, so they'll definitely be keeping him around.
I'm not counting Civale as a lock, unless he really impresses in the post season. At the same time I think the Brewers and Murphy have a lot of trust built up in especially Milner, but also Payamps and Wilson.
As far as the Rule 5 guys, I think it's Henderson only. Maybe Shane Smith makes it, but the Brewers don't tend to protect fringe-y players. That Nashville rotation should be stellar: Mis, Henderson, Ashby, C-Rod, Smith.