The first part is correct, the second is not. Take man off the land and nature does just fine, reforests all by itself. Nature did it before and will do it again without man. Nature reforests, man strips the land.
There is no new savings, replenishing the account, for coal, oil and NG. You're correct that as these become more expensive, necessity will force a change. But in the meantime we are using up the savings that would be there for future generations, and not only using it up, but wasting most of it on really quite frivolous things, kind of like spending the retirement/pension funds on expensive travel and dining that will deplete those funds long before a person dies and really needs the funds for essentials. "Long before a person dies" is the equivalent of future generations; they too will need these precious resources for essentials; but the current generation is spending them now.
We really are pretty close in agreement. I just think we now should pay the real cost of our use of energy resources (environmental cost, pollution cost, health cost in disease and death, etc.), which would "force" a change, and instead now use sustainable and renewable energy resources rather than spending the wealth that could be saved for the generations that follow. We are living on borrowed time, let's stop the borrowing.