Offline Mode's need for online setup has caused a headache for me in the past. When I had an internet outage and couldn't get online (hence a rare desire for offline mode), I discovered I had not done everything I had to for Offline Mode to work and was locked out. Awkward. If Steam were to create a contingency for this, that would be sweet.
Of course, if it's all set up in advance, no worries...
Of course, if it's all set up in advance, no worries...