I don't like to admit this, worst case. When I was young and stupid, I forgot to hook the lanyard to myself, fell off the ski while jumping a wake. The ski slowed to an idle, made gentle left turn, and litterly waited for me to swim to its path. I pulled the lanyard and got back on, hoping no one saw me.
While I wouldn't recommend trying this, worst case the ski is NOT going to continue to run down the lake at 50mph, its going to slow to an idle and make a left circle, and almost come back to you.
Lou