The temperature change is not the dangerous part of climate change for countries away from the equator. It's all the other changes that accompany that, which will affect Novosibirsk too directly or indirectly. Like loss of biodiversity, climate refugees, unstable political situation, etc.

I do agree with you that Canada and Russia are likely to suffer the fewest negative effects. But I wouldn't say it would be a net positive for them either. It's not impossible, but there are a lot of unknowns at this point and a lot of potential feedback loops that could be devastating, like mass extinction level devastating.