People at http://www.longrangehunting.com website claim being able to hunt and shoot elk out to 2000+ yards...
They even have a forum for:
"Ultra Long Range Hunting for the 2000 yard hunters"
I believe if you can do it all the more power to you. However, 99 % of us hunters probably never will or will never develop the shooting ability for such shooting. How far is too far for hunting elk?
Remember, there is no right or wrong answer here, just your opinion on how far YOU personally shoot.