But then you'll die of hunger or thrust, which isn't a good situation to be in but, it happens now as well. People get trapped in remote, abandoned places only to die of circumstances other than natural causes.

I suppose that the biological immortality that author has talked about, the kind that our future generations will see, will still require all the necessary resources like we do. They'll still get sick and will need medical care sometimes, environment will still affect them, the only thing that will change is the deterioration that our body goes through as we age. I don't know much about the concept but I think it is pretty easy to picture it.