The likelihood of human survival on this planet without vegetation is nil. This is because of the symbiotic relationship between vegetation, our atmosphere and each living organism that derives nutrients from vegetation. This in turn provides food for insects; insects become the food supply for higher animal life forms and so on. In this way almost every living thing on the planet forms part of a complex living matrix with interdependency between multiple singular elements.
History has recorded the rise and fall of literally millions of different species far back in time. The most notable example of life disappearing from the planet was some event of approximately 60 million years ago where speculation suggests the impact of a massive celestial body darkened skies on a global scale. Plant life died and subsequently most living creatures also died. It was only the exceptional that managed to survive, mostly these seemed limited to reptiles and sea creatures such as sharks and rays.
Trees and vegetation replenish our oxygen supply by absorbing CO2 and then releasing oxygen. It is for this reason the Amazon jungle is frequently referred to as the lungs of the earth' and this planet seems to be experiencing a growing problem with significant atmospheric changes some believe are related to the deforestation of the Amazon. Other vast tropical forests in Asia are laid waste by greedy corporations harvesting valuable and in may cases quite rare timber species used to adorn domicile of the wealthy.
With the rapidly accelerating rate of deforestation entire species are becoming extinct. Incursion of human habitat into the natural world displaces thousands of animals which then face the challenge of adapting, or they die. Most are incapable of adapting. Given the interdependency between vegetation and animal life it is only a matter of time before a critical point is reached where the consequential damage destroys a key element of the planet's matrix of life and triggers another global extinction event.
Irrespective of how advanced technology has become humans are no more capable of adapting to and surviving a massive die-out of almost all other life forms. Reverting to eking out a living by scavenging will not succeed because we have come too far down the evolutionary path and our bodies could no longer tolerate this kind of nutrient. Our only chance of survival is to clean up our act, clean up our environment and look to sustainable industries for raw materials. Protecting forests and plant life is an essential condition to our longevity as a species.