If they trade a d-man (Eckholm or Ellis) as the key piece, they could protect more players because they wouldn't have to go 4F-4D in the expansion draft. Not saying that either team does that deal, but it would make sense IMO for the Preds to at least consider that.
EDIT: Never mind. I was under the impression that Arvidsson didn't have to be protected, but that's not the case, so he'll definitely be the 4th forward protected.
It's a consideration. Right now, if Poile were to protect all four top-4 defensemen and the top three forwards (Neal, Forsberg and Johansen), he would then have to decide between Smith, Wilson and Jarnkrok and likely lose one of the other two. Wilson probably won't be protected or selected (paid too much for too little production), so it comes down to Smith, the 20-goal scorer whose $4.25M cap hit is a little rich, and Jarnkrok, the 15-goal scorer with a mere $1.9M cap hit. I think that Poile would protect Jarnkrok. The question, then, is whether Poile would be OK losing Smith. In some ways, getting that $4.25M cap hit off the books would do him a favor. On the other hand, his 20 goals are valuable to a Preds team in need of scorers.
If Poile were to trade Ekholm or Ellis, then he could suddenly protect 7 forwards, instead of 4. That would allow protecting all three of Smith, Wilson and Jarnkrok
and the forward that he gets in trade for Ekholm/Ellis. That could be tempting for Poile. At that point, all that he would have to worry about is losing a 4th-line plugger like Cody McLeod or Colton Sissons or defenseman Matt Irwin, all players that are easily replaceable in free agency.