Here's the current contract situation for both nations (hopefully I didn't forget someone):
Slovakia:
F
Juraj Slafkovsky
Martin Pospisil
Dalibor Dvorsky
Samuel Honzek
Adam Sykora
Filip Mesar
Jakub Demek
Juraj Pekarcik
Martin Misiak
Oliver Okuliar (RFA)
Martin Chromiak (RFA)
Tomas Tatar (UFA)
Pavol Regenda (UFA)
D
Erik Cernak
Martin Fehervary
Simon Nemec
Viliam Kmec
Samuel Knazko (RFA)
G
Samuel Hlavaj
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Latvia:
F
Teodors Blugers
Zemgus Girgensons
Rodrigo Abols
Eduards Tralmaks
Sandis Vilmanis
Dans Locmelis
Eriks Mateiko
Raivis Ansons (RFA)
D
Uvis Balinskis
G
Elvis Merzlikins
Arturs Silovs
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Slafkovsky, Pospisil, Cernak, Fehervary and
Nemec should play reguarly in the NHL among the Slovaks.
Dvorsky and
Honzek are highly likely to see games as well. I'm also guessing
Sykora will make his NHL debute at some point next season.
Okuliar had a strong year in the AHL and could do the same.
Regenda also a possibility if he's willing to keep battling in the minors instead of returning to Europe. I'm assuming
Tatar is done in the NHL, but it's a 32 team league now and teams always need veterans for training camp, so who knows.
Blugers, Girgensons, Abols, Balinskis and
Merzlikins should play reguarly in the NHL among Latvians.
Silovs is the first callup in Vancouver in case Demko/Lankinen gets injured in Vancouver.
Tralmaks is 28 so he should be fighting for a spot in the lineup in Detroit. If he doesn't make the team he should have a very good chance to be called up in case of injuries.
Locmelis is an interesting prospect. Maybe will spend the whole season in the AHL, but wouldn't be surprised to see him get a cup of coffee already.