I have seen more winter commuters around here; challenging to say the least with all of the ice and snow. Last summer and fall there were definitely more people riding, both for commuting and recreation.
When my son was home on leave one thing he noticed was the incredible increase in the number of women cyclists around here since the time he started riding in 1999. He sat down on the town green with his bike and had quite a few younger women challenge him to a ride!
I think more people will exercise as a stress reducer; maybe they won't all ride, but walking, hiking, and running are essentially free if you have shoes. And yes, I think a lot of people will be pulling out old bikes.
I am not riding more, but I am exercising more, trying out a variety of things. It keeps my mind clear for all of my studying and also to deal with the fact that I still need to get an offer for an internship position for next year (where they don't even have to pay me!).