I agree that commands should start with $ to show what the user types vs what the program emits. But this doesn't make it easier to cut and paste, so that phrase needs to go. 

I also don't like talking about future hypothetical features and using them as reasons to change something now. If we/you do make an automated output tester, we can go back and change all the code examples then. So please remove that phrase as well.

The sentence then becomes "Start typed commands with ``$ `` so that they are easily differentiated from program output."