Hieskanen is great, but he's the only Finnish defender who'd make the starting roster of Canada, USA, or Sweden. As for Russia: goalkeeper depth is almost a curse rather than a blessing, unless they can figure out some genius system that involves having multiple keepers on the ice.
I think Cernak would enter into consideration for any national team, if not make the final cut, given that the postseason is "real" in a way that the regular season isn't, and that Cernak has been an important part of Tampa's playoff achievements. Him and Fehervary would both be guarantees for Russia and Finland. Rasdim Ristolek would be playing behind Hronek and Rutta, as far as right-shot defenders go.
I'm only kidding around with you about this stuff, but that doesn't mean I don't mean it. Czechoslovakia has a great history in hockey, one which both present nations could regard as their own. It's unfortunate to see its two successors reduced to mediocrity (Czech Republic) or off the map entirely (Slovakia, now definitively behind the Swiss and Germans, but at least finally showing signs of recovery).
Czechoslovakia wasn't a large country, and population isn't everything, but being a smaller country automatically means playing at a higher difficulty setting. For comparison, even a united Czechoslovakia would only have a population between 1/9 and 1/10 that of Russia. The US state that I live in has over 4x the population of the Czech Republic.
On the bright side, things are looking better at the junior level, and yes, there were the Czech/Slovak teams of the 90's and early 2000's (although Slovakia was screwed over by the IIHF and Olympics, so that team almost never saw the ice). Still, it doesn't seem likely either will be able to return to the sporting status of the formerly united state. (And yes, I'm aware that there are issues more important than an ice-game at stake here, but it's not like there was any actual ethnic or sectarian strife, in your case).
...different topic, but sort of related: It's always struck me as odd that European countries, especially if they're smaller countries, almost never combine their top levels of domestic sports competition. Is there any good reason the Czech Republic and Slovakia don't have a shared competition, instead of the separate Extraliga(s)? It seems like self-sabotage for smaller countries to not pool their resources.