I don't think this kind of forehand can last at the pro level. I see it as a huge liability that needs to be changed ASAP. At the pro level, it will not provide enough stability, accuracy, or power, nor will it allow for minute split second adjustments that are often required. The off arm stretched out (usually parallel to the baseline) provides the stability that is absolutely necessary to compete in today's men's game. The whole body working together (in the coiling and uncoiling phases of the forehand) is a necessary component of the modern forehand.
Natural athleticism can only take someone so far....