You should at least bring up the story of Max Planck in the late 1800s. He was basically told not to enter physics, because supposedly nearly all of physics has

You should at least bring up the story of Max Planck in the late 1800s. He was basically told not to enter physics, because supposedly nearly all of physics has already been discovery. We know what came next in physics. We don't know the future, and there's no way to say for sure that we've see the last big changes in life. Your grandparents could be proven laughably wrong in next few decades. That said, it is likely at this point that we've exhausted the current paradigm. That there isn't much left to gain in maximizing existing scientific theories, or pumping billions into mature technologies. These concepts and philosophies have failed to real creating something of note lately, and that might be a sign that they are at their limits. So the next step would be a step-change function and something completely unexpected.