How much could financial sanctions on Russia hurt the West?

If the crisis in Ukraine escalates further, the West seems more likely to impose limited financial sanctions against Russia than to target trade in goods, especially energy. Some Russian officials have flagged up the risk that Russian borrowers might then be forced to default, or even that the country might retaliate against the West by choosing to renege on its debts or dumping foreign assets. However, this is an arena where the risks to Russia far outweigh those to the rest of the world.