There is a console command that lets the camera get farther. It looks weird, though, due to fog and some of the stuff that's normally off-screen not rendering. Let me find the command and take a screenshot.
EDIT: The command is dota_camera_distance. It's default value is 1134.
At 2000, it looks like this.
Then at 3000...
The fog also changes colors between the Radiant and Dire side, which looks really jarring when you cross the border with a further camera. However, with disabling the fog, and maybe doing something with the draw distance, some cool stuff could be done with it.