That's true but they have one huge advantage over almost every other team in that tourney in that they play high level league (USHL) hockey together as a team all year before this tournament. Most of the other teams, especially Canada, are basically 'all star' teams.
Having just looked up their stats, I notice there's a whole bunch of 94 born kids on this NTDP U-18 team, possibly they're in kind of an in between sort of year (gearing up for a big year next year?):
http://www.hockeydb.com/ihdb/stats/csl.php?tid=5434
Forwards: Samuellson, Kerdiles, DiPauli ; D-men: Seth Jones , Trouba
The above would all be underagers (94's) to watch for at this tournament
Top guys over-all should be forwards Grimaldi and Biggs. The 93' d-men sure don't have any rep compared to the group that came through 2-3 years ago.
There's not, at least currently, any '94s playing with the U-18 team. That list includes both the U-18 and U-17 teams, although some of the '94s have played a handful of games up this year. We'll probably see a couple of those guys move up, maybe permanently, to the U-18 team soon though. It usually happens after the New Year like with Grimaldi last year and eventually Biggs.
It's probably too early to get a real good read on who might move up from the '94 forward group, but I think you target some of the likely candidates. The '94 d-man group is really deep and they have lots of choices but Trouba or Jones are the headliners at this point but guys like Skjei or Carrick could get looks as well. There's also Nick Ebert from Windsor, in which they should do whatever necessary to add him if he's available. Given the weakness of the overall '93 group of d-men for the USA and the NTDP team, coupled in with they've been missing one of their best guys there all year again in Connor Murphy, and I wouldn't be surprised to see them add 2-3 d-men for the tournament.
Typically the team doesn't go overboard outside of the NTDP teams to make their U-18 team for the tournament but this might be a year they do so. They normally (if ever?) don't just leave guys off the roster but they will demote guys to the U-17 team but it's typically been to promote someone from the U-17 team up for the tournament. It'll be interesting to see if they're willing to demote someone in favor of someone from outside the program, especially at forward, with guys like Alex Galchenyuk, Seth Ambroz, Shane McColgan, Colin Jacobs, Stefan Noesen, Vince Trocheck, Cason Hohmann, Mario Lucia, etc. all potentially available but depending on playoff scenarios of course.
For last year's tournament, they added Connor Brickley (USHL), Austin Watson (OHL) and added Tyler Biggs and Rocco Grimaldi from the U-17s.
In 2009, they added Philip Samuelsson (USHL) and Jack Campbell, Jon Merrill, Adam Clendening, Matt Nieto, Jason Zucker from the U-17s.
In 2008, they added Aaron Ness (USHS), Philip McRae (OHL), and Brandon Maxwell, Ryan Bourque, Jeremy Morin, and Kyle Palmieri from the U-17 team.
In 2007, they added Tom McCollum (OHL), Tommy Cross (USHS), Ryan McDonagh (USHS), Jimmy O'Brien (NCAA), Patrick White (USHS), and Vinny Saponari and Jordan Schroeder from the U-17 team.