Also, the "back to nature" movement may gain traction. People with diverse knowledge and experience on these issues will be much sought after in such a future.
I've arranged with an elderly friend to revive her vegetable garden, and I will start to post progress here as a "wild brambles" project. This isn't so much a get rich quick project, as a convenience for both of us. Maybe I can scratch a few pence from a blog, but there are a lot of people doing the same thing.