BTW, that multiple tech revolutions can happen in 20 years point argues for longer not shorter patent terms. If at great effort and expense, I develop and patent a nuclear powered widget and then four years from now the market moves on to quantum-based widgets, why should my nuclear powered widget patent have a shorter patent term? If a patent is an incentive for me to invent (and it is) then increasing the velocity of technology while keeping RD costs constant and then shortening the patent term dis-incents me.
Of course any creator of patented nuclear powered widget wants the patent to exist longer, not shorter, because it's easier to make money. But shortening patent life is for world progress' sake, here the most beneficial strategy for individual might be not the most beneficial strategy for the world. Progress is in many ways evolutionary and future inventions are based on the previous ones. So if you would make patents indefinite in time, you'd effectively remove this step from progress and will make it work around (also disincentives creator of patented technology to innovate, if it's market leader it can also slow down everything), possibly slowing it down. Patents make sure that inventor have time to return investments, it's a balance exercise. Nowadays world communicates/works on much faster speed and contains much more people/companies that's why I think this balance should be moved to the shorter patent length.
