it would involve A LOT of retooling. I think its possible, but I'd have to literally recode most of worlds in order for it to work. Might be a fun side project after SC2 is done.
Now that I think of it, it's probably not really necessary, as long as the leader is stored in a variable for the code to check out: "if this is the leader character, do this, else, do this instead", or "do this for every character except the leader". That way, you can have as many followers as you want, but the code would be character independent. I had another idea for this, but it's a bit gimmicky and I can't remember how could it be made, so I've chosen the easy answer.