It is important to realize that consciousness is not something that materialism (meat-machine) can explain. There are non-material realities, starting with numbers and moving on through symbols and meaning towards mind. What is this thing called mind? And who is it that is asking the question?
Does the brain generate consciousness? Or does the brain receive consciousness, like a radio receiving a signal? In that case the signal would not be affected by the breakdown of the machine. Choose your metaphor carefully, people.
Hancock argues that the current civilization has gone insane by denying that we are spiritual creatures (viz. that buffoon Dawkins, and his allies Daniel Dennett, Sam Harris, Christopher Hitchens and others) and that a spiritual domain is real. He concludes by insisting upon the right of the sovereign individual to affect their consciousness through the responsible use of mind-altering plants.
You do not have to agree with all of Hancock’s elegant rant, to consider that our world civilization is in one of those eras that most stridently and intolerantly denies the spiritual as being real or in any way important. In that sense it is not sustainable, because it denies the existence of the most important part of who we are. We are not meat-machines.