There was an article in USNI that noted that the over Canada route is probably the only economically viable one for shipping, due to straits restrictions for Russian routes 9specifically 7m and 13m depth restrictions for two specific straits). And even still, "economically viable" is a relative question.
Some of the similar issues are touched
upon here (I vouch nothing for that blog on other than that post).
Arctic warming will probably help Russia more by making more petro deposits viable than by opening up shipping routes.