I believe Kangas is a player that could get selected for third pairing. Don't believe all the "Best" D's when it comes to skill will get picked. So yeah, the third pairing and- or perhaps the second could consist of surprises.
Also, what about Soini? I mean isn't Ilves one of the most competitive teams or rosters for a young guy? Muhonen is another one like Kangas, could be a lower pairing D. Junkkari and so on. These guys could go before someone like Nieminen, Nykyri and Jokinen.
Otherwise like you've mentioned, very difficult to guess the D lineup in the end.
Hemming, Väisänen and Nurmi have pretty weak showings over the seas so far. Especially Hemming who probably gets more opportunities. Väisänen could likely have played himself out of the roster already.
For me right now:
Locks: Rimpinen, Vali and probably Saarinen because of Vinnis injury.
Kiviharju, Pieniniemi.
Kumpulainen, Miettinen, Helenius, Vesterinen, Saarelainen, Rautiainen, Halttunen, Hynninen, Kiiskinen.
Will probably get selected but not locks: Koivu, Kuusla, Hemming.
Outsiders amongst forwards: Huttu, Alasiurua, Sinivuori.
Overall i have to write that the depth amongst the 2006 born players is pretty deep compared to earlier and following years. The 2007's just shouldn't be mention from a Finnish perspective lol.