And to expand on this, it's not realistic because science is not armchair philosophy. You have to go out and measure the world.
Sometimes, through force of will, a person can think deeply about a problem and come up with beautiful theories that explain our measurements. Many scientists had careers like this, probably most famously, Einstein. But it's worth noting that Einstein also got a lot wrong! [1]
Even if we somehow give an LLM the ability to go out and measure things, I seriously doubt that the role of humans in science is done. There's a big difference between "an explanation" and "a good explanation." Ask any physicist. There's a surprising amount of aesthetics involved. Good theories are consistent with the evidence, but it's more than that-- there's a great deal of "taste" involved. And there's a good reason for that. For any real problem, there are effectively an infinite number of alternative hypotheses. From a "theory of science" standpoint, this should cause scientists nightmares, but it doesn't. Because by the time you are a practicing scientist, you've developed a feel for what constitutes a satisfying explanation. If you spend time with scientists, especially in the "hallway track" at a conference, "taste" is a frequent topic of conversation!
[1] https://en.wikipedia.org/wiki/Einstein%27s_unsuccessful_inve...