Listen...!

Well, that's kind of redundant, you can't scientifically 'study' something without being able to 'observe' it. That's like part of the definition or something. Hence, for what we cannot observe, we can only speculate. Theories remain theories until they are proven. We may not know everything, but what we do, it's because it's been proven. Because of that, even if we do learn more things about the universe, what we 'know' now, won't ever become irrelevant.