Newton was wrong, Einstein has provided us a better, more accurate, theory of gravity. Guess what? We still teach Newton in high school and college physics! Why? Because though it's wrong it's only wrong in the most extreme circumstances. Generally speaking it works quite well. The only observation we made contradicting Newton was Mercury's perihelion precession. But Einstein didn't change how fast apples fall to the ground.
Likewise, we know, or at least strongly suspect, Einstein is wrong. That doesn't mean everything we've observed the past 100 years corroborating General Relativity goes out the window with a new theory. No, instead that's what makes creating a new theory hard: you have to account for a century's worth of observations validating GR and reconcile with QFT (otherwise why bother).
But it wouldn't change anything about what we already know and what we've observed. That's why it's a boundary box. This is science, not magic.
I've read the article. It exposes a well-known point of view in philosophy of science that has been debated at least a hundred years. It doesn't begin to cover that question at all.
Notably, the idea that a new theory simply takes existing "observations" and adds to them is historically unfounded. Indeed, many theories start as thought experiments that contradict observation and later turn out to be better models, not the other way around.
You also may or may not be familiar with the concepts of theory-ladenness and the commensurability of theories. If not, I suggest doing some reading about that so you can appreciate why those questions aren't as straightforward as you seem to believe.
A new theory isn't going to contradict your observations. It may provide an alternate explanation and allow you to understand the phenomenon a different way, but the phenomenon leading to the observation is unchanged.
This is important in this discussion because we've never observed anything traveling faster than the speed of light in a vacuum. That would appear to rule-out faster-than-light travel, which for practical reasons would make traveling to other solar systems impossible.
Newton was wrong, Einstein has provided us a better, more accurate, theory of gravity. Guess what? We still teach Newton in high school and college physics! Why? Because though it's wrong it's only wrong in the most extreme circumstances. Generally speaking it works quite well. The only observation we made contradicting Newton was Mercury's perihelion precession. But Einstein didn't change how fast apples fall to the ground.
Likewise, we know, or at least strongly suspect, Einstein is wrong. That doesn't mean everything we've observed the past 100 years corroborating General Relativity goes out the window with a new theory. No, instead that's what makes creating a new theory hard: you have to account for a century's worth of observations validating GR and reconcile with QFT (otherwise why bother).
But it wouldn't change anything about what we already know and what we've observed. That's why it's a boundary box. This is science, not magic.