I dont think it would be very profitable. I am sure it would be banned from tournaments as soon as the word got out.
I also think it would be expensive and it would probably be difficult to make it durrable. You see a robot fish swimming in a pool and it looks cool but its not being casted. Its not being shaken violently by a big fish or what if it hit rocks etc.
I do belive at some point sombody will pull it off but there are some big hurdles to clear.
Rob you find the robotics expert willing to do it and I will help with the cosmetics and action :-)