It would be arrogant to say that science has had its heyday and that all the big discoveries are behind us. The universe is as complex as it is large. The need for good science will never go away.
Imagine if we had stopped physics research after Newton had worked out calculus and classical physics. Imagine if we had stopped biology research after Henry Gray published his text book on human anatomy.
Isaac Newton was a brilliant person. He figured out the motions of the planets and worked out his now well-known three laws of motion. He discovered that the planets do not revolve around the sun but the planets and the sun all orbit around a common center of mass. In the process of doing this, he had to come up with differential and integral calculus.
However, Newton was confounded by something. He and other astronomers kept detailed logs of the planets’ motion in the sky. They indicated that the planets’ orbits were not constant; they were constantly being perturbed by the gravitational pull of the other planets and other objects. According to all the math he had done up to that point, he found that the planets should be knocked out of their relatively stable orbits. Rather than try to solve the problem, he supposed that there was a divine hand in keeping the planets in the proper places in the sky.
The is the tragedy of Isaac Newton’s life. He was undoubtedly smart enough to figure out this perturbation problem but he did not. It was another 200 years before a comprehensive description for perturbation theory was established.
Because we might be amazed at what we have discovered or that we do not know what we will discover in the future, that does not mean that we should not expect to discover anything. The universe is huge and our understanding of it is anything but complete. Until we are absolutely certain of everything, then scientific advance has to continue on.