Per Vaughn McClure at ESPN, both players are working their way back from major injuries and may not be ready for training camp when it opens on July 25th. Peters is coming off an Achilles tear and was able to do some "light running" during minicamp, which is an important step, albeit one that all of us hoped would come before mid-June. Motta hasn't practiced at all as he works his way back from a significant back injury.
McClure notes that Peters could be placed on the Physically Unable to Perform (PUP) list for training camp, which would leave him unable to participate in practices until activated. If Peters can't go for any reason by Week 1, the PUP list could be an option, though it would keep him off the field for the first six weeks of the season. We know he's working hard to come back, and for now, I'm still reasonably optimistic he can be on the field in the first couple of weeks of the season.
Motta is a different story entirely. I agree with Aaron Freeman's take on Motta's cervical fracture over at FalcFans:
It’s clear that Motta’s neck injury is a career-threatening one.
Mike Smith told McClure that Motta has an appointment in July that will help determine his status for the upcoming year, but I'm not overly optimistic. The best-case scenario for Motta might be starting the year on PUP even if he's recuperating nicely, and hitting the IR and using 2014 to try to recover if that's not an option. A cervical fracture isn't impossible to return from, but it requires extra care and time, to say the least.