Ether that you own (not related to the DAO) before the fork happens would be unaffected by the fork. But after the fork, suppose you accept payment for something. You can accept payment in cash, Bitcoin, Ether-on-left-side-of-fork, or Ether-on-right-side-of-fork. I suppose you could also insist on getting paid in BOTH "Ether-on-left-side-of-fork" and ALSO in "Ether-on-right-side-of-fork", but that starts to get really complicated.
In practice I think I'd sooner switch back to a non-forked cryptocurrency than try to deal with running multiple forks and ensuring that I'm getting paid on all of them. That sounds like a right huge mess to deal with, as you point out.
