Yorman and Duran would have to have complete disasters in 2012 to not be protected, simply because of the monetary investment the organization has already made in them. Most players have to prove they can play, but a few have to prove they can't. When you get $2 million plus, you will get chances to prove you can't play until you prove it beyond any doubt.
Guillon, I believe, has already been Rule V eligible for the last couple of years due to an administrative matter that voids the five year rule. I think Guillon will need a good spring to make the Dayton club. A good spring in this case would mean he shows up without the same control issues that popped up and gave him fits in 2011 (46 BB, 13 WP in 63 IP).