I believe there's a decent chance Brice Butler could pleasantly surprise many Cowboys fans if he's afforded a chance to demonstrate his potential. He's already had two very productive offseasons with Oakland. Despite that happening, they chose to go with experienced veterans, hence curbing his development.
There are many in the Bay area and elsewhere that feel we fleeced Oakland in that trade and are disappointed that they curbed his development in so doing. Lately, the Raiders allowed Butler to get away to clear a roster spot, which enabled them to make a hasty trade to get an experienced safety. It's entirely conceivable that such a decision could, in time, become an embarassment to them.
Since Romo has already proven what he can do with someone like Laurent Robinson. It wouldn't be terribly surprising if he were capable of repeating that feat with Butler in Dallas. Given enough time to familiarize him with their offensive system, that same scenario might be duplicated. If it happened once, it could happen again.