USA will definitely be a good team but I've seen a lot of projections with your 1st line, Krys on the top pairing. Roslovic, Matthews, Tkachuk were a dominant line for the NTDP but as a top line at the World Juniors is asking too much IMO. They are '97s, they'll be underagers and their chemistry will only take them so far. Roslovic won't be a great player at the WJC against the best U20s. I don't think Roslovic should make the team because he's just not good enough. The 2nd line should be the 1st line IMO, all '96s with good amount of talent. Krys on the top-pairing will not work. He's small, a double underager and I don't think he should be playing big minutes against bigger, stronger players. He's not an exceptional player either. Matthews should play on a 2nd line where he is used as a secondary scorer, Larkin, Milano, Tuch are both more mature, older, and should be able to carry the offence for USA while Matthews is used in a secondary role where he doesn't have as much pressure.
I just don't think you can expect to put a NTDP line who played USHL/NCAA teams previously against national U20 teams and expect them to continue their production. It probably won't work because they are playing much better competition.