Tyler Biggs is not a lock. He's on the outside right now and probably not close enough to even be looking in at a potential spot. Plus, there's current players better at the "physical pest" role than Biggs right now. Look for guys like Knight, Arnold, Brickley, etc. to fill those roles.
Brandon Saad isn't a lock either. No one knows, or is telling, why he declined his invite to the Summer Camp. Those with contacts to the inner workings of them team don't know. Some have speculated he was injured but if that were the case it would have come out, and USA Hockey would have just announced it. Either way, it doesn't bode well for Saad's chances of even getting a return invite for the December camp.
Justin Faulk is one to keep an eye on. He'd be the team's best defender and while I still suspect he'll be available for the tournament, the team could be hurt if he's not available give that Connor Murphy (another lock) is most likely unavailable, combined with Jon Merrill's uncertain playing future in the short term. If he can't go, and Murphy doesn't come back sooner than expected and in form, it'll be interesting to see where they go. The '93 d-man class isn't deep. Would be interesting if they choose to go more defensive or if they'd look for another young guy (in addition to Seth Jones) like Nick Ebert, Jacob Trouba, or Jordan Schmaltz to possibly fill in.