When the question for my answer here was changed to CW, I think my answer should have been made CW as well.
As other noted, the only "wiki-hammer" occurs when a question reaches 30 answers and is not already community wiki. At that point the Q and all As are forced into wiki.
Thus, any poster can opt in to wiki at the time of post, without affecting any other questions or answers.
(it is not possible to opt out of wiki, ever, though.)