The argument is that economic sanctions will in fact constrain the Russians from meddling in places like Ukraine, Crimea, and Georgia. We all hope that is the case.
I would just say that there's another low possibility alternative that should worry us a great deal. Prior to World War II, the United States used sanctions very effectively against Imperial Japan with very bad results. What one needs to do is have a deterrent in place that is convincing and compelling, and then one needs to use economic sanctions as a further source of leverage. If one just relies on the economic sanctions and you don't have the deterrent in place, you can sometimes see some very bad results.
I trust that will not be the case with Russia in this instance, but it's something we have to be concerned about.