If history is any guide, Russians are good at tolerating hardship. Putin has built a pretty powerful police state. Of course, if he is perceived as being crazy or making blunders that are too serious, then it could get difficult.
For Russia to march across Europe, they'd have to mobilize their reserve. As we speak, the economic capacity needed for that is being dismantled and I don't think China would stand for that for a second, so no support from China.
Yeah in history they did tolerate hardship, but the last 30 years after the fall of the USSR has raised a different generation. How many under 30s really want to fight a war, let alone a war against countries they might have traveled to on holiday to go shopping? Countries where they have friends from the Internet in? Does a millennial want to fight for their country?
I think the culture of what those reservists might look like, needs to be considered.
Will head to bed and sleep on it :)