I love David Hayter, but remember that he kinda fell into the Voice Acting thing, and is actually a writer. He could be busy with other projects, and he is rumored to be working on "Man of Steel" and the "Justice League" movie. Remember, he co-wrote X-Men (the first) and worked with Zack Snyder on Watchmen.
My guess is that he may be very busy with something else and it would be difficult for him to stop and go act. I still think that his MGS4 performance is one the best in any video game, and would be very dissapointed if he did not come back, but I do not think it would be a deal breaker.
My guess is that he may be very busy with something else and it would be difficult for him to stop and go act. I still think that his MGS4 performance is one the best in any video game, and would be very dissapointed if he did not come back, but I do not think it would be a deal breaker.