There is no longer any kind of automatic Community Wiki conversion of questions and answers. No matter how many editors or revisions your post has, it will never become Community Wiki now. The only way a post will ever become Community Wiki is if someone actually manually turns it into such. All automatic triggers are passed on. They are no more, they have ceased to be, they have expired to go and meet their maker; bereft of life, they rest in peace.
This is a part of the system we've lived with for a while, so this is just me trying to get the word out that it's gone.
You can read more about it in this blog post: Putting the community back in wiki. It's kind of amusing, too.
So go forth, and edit your posts a dozen times if you want to, with no fear of community wiki conversion happening.