With the twenty or so DC movies that WB is already supposedly working on, I'm highly skeptical of a Supergirl movie happening any time soon. Much like with the Flash, the current TV show already covering all the classic material and doing a fine job of it makes a potential movie seem a little redundant. Interestingly enough, the one capeshitter whom I think is both well-suited to exist in separate continuities on film and television and could avoid audience confusion/burnout is Batman. He can be a gritty, vengeful brute, a charming, suave adventurer, a wholesome community figure, and so on. This is partially why Batman is the best capeshitter.