I don't believe the Packers would have drafted Perry in the 1st round if they didn't expect him to be good enough to start immediately. They might limit his snaps if he struggles in some situations, such as obvious rushing downs or on defensive calls when they need a linebacker to drop into pass coverage, but I expect he'll start one way or another.
While the Packers should keep six (or seven, if a linebacker is kept on the practice squad) of the remaining nine players listed, I have no idea who they might be. It all depends on whether they can stay healthy, and how they play this preseason.
Francois has been cut before, so he's not a lock. Jones has been in-and-out of favor for the past three seasons, he's been lining up inside this summer, and he'll need a strong camp to stay. Lattimore looked good last preseason, but he did little when he had a chance to play during the regular season. Smith might be the one sure thing among the backups, but a poor preseason could doom his chances too. So'oto followed an outstanding 2011 preseason with a MIA regular season due to injuries, and he did little when he was able to play. Walden received little interest in free agency, and despite his limitations as a pass rusher and in coverage, he's probably the best outside LB after Matthews and Perry. Zombo had a lost 2011 season due to multiple injuries, and he'll have to prove that he's healthy and productive. Overall, there's a lot of potential with the returning backups, but an awful lot of question marks too.
Finally, Manning and Moses are the other promising new additions. Manning looks like he could be a solid middle linebacker in coverage, and he could be a Brandon Chillar type of player. Moses has been the star of the OTAs, the undrafted player who's already earned some reps with the first team defense. It's very early in their careers, but so far so good.
Overall competition level: high. There are a lot of good players here, and at least one promising player or former starter is going to find himself released before the start of the regular season. The Packers needed to upgrade the position, and they've certainly done it.