Well observed. In addition to laws of physics and beyond, the so-called "law of supply and demand" remains in force. This includes in the animal kingdom when the required balance of "prey and predator" can only swing away to return to some sort of balance between them.
"...to supply Earth's energy needs for several thousand years" is probably right here on our little bit of the Creator's great work, far greater than we can even conceive.
As long as there are ruminants, there will be methane.............
I agree with your theory about our Creator’s plans for our world. God is endowed with all wisdom & we are only slowly learning.