By every possible means, presumably. Okay, seriously, she thinks we can test such a theory in principle, but…
But what you really wanted to know, I guess, is whether these tests are practically possible any time soon? I do think it is realistically possible that we will be able to see these deviations from general relativity in the next 50 years or so. About the other tests that rely on models for the early universe or symmetry violations, I’m not so sure, because for these it is again possible to move the predictions and then claim that we need bigger and better experiments to see them.
Is there any good reason to think that such a theory of everything is correct in the first place? No. There is good reason to think that we need a theory of quantum gravity, because without that the current theories are just inconsistent. But there is no reason to think that the forces of the standard model have to be unified, or that all the forces ultimately derive from one common explanation. It would be nice, but maybe that’s just not how the universe works.
Sabine Hossenfelder, “How can we test a Theory of Everything?” at BackRe(Action

Sabine Hossenfelder is the author of Lost in Math: How Beauty Leads Physics Astray.
See also: Slapping Sabine Hossenfelder Isn’t Going To Solve Physics’s Problems
and
Sabine Hossenfelder: There is a crisis in physics and it may spread to other sciences
Better yet, “How Can We Test The Theory Of Evolution”?
http://nonlin.org/evotest/
as to this comment:
A refreshingly honest confession.
as to:
Another refreshingly honest confession.
In fact, the belief that there should even be a single overarching theory of everything is a belief that is born solely out of Theistic presuppositions.
And as Einstein himself stated,
Moreover, as Godel has shown, via his incompleteness theorem, there simply is no reason that theoretical physicists should even presuppose that mathematics, all by its lonesome, will ever yield a complete ‘Theory of Everything”:
Moreover, according to work done by leading Mathematician Gregory Chaitin extending Gödel’s incompleteness theorem, we now know that what “Gödel discovered was just the tip of the iceberg: an infinite number of true mathematical theorems exist that cannot be proved from any finite system of axioms.”
Thus, as long as theoretical physicists erroneously believe mathematics to somehow be a ‘brute fact’ that can potentially explain everything in a single mathematical theorem, and forget about the God who brings unity to the universe, (as well as to mathematics), in the first place, they will forever be barking up the wrong tree.
Might I be so bold as to suggest a far more satisfactory ‘theory of everything’? A ‘theory of everything’ that even goes so far as to explaining the exact reason why he universe exists in the first place?
For a promising new quantum theory of gravity, please see
Proposal for a new quantum theory of gravity III: Equations for quantum gravity, and the origin of spontaneous localisation
Maithresh Palemkota and Tejinder P. Singh
arXiv:1908.04309
https://arxiv.org/abs/1908.04309
Tejinder
nonling@1
such an irony – Darwin’s theory of evolution and common descent, can’t explain the existence of the MOST ABUNDANT organism on Earth – Viruses.
Most abundant organism on Earth, but their theory can’t explain it 🙂
Of course, Darwin had no idea about viruses.
Educated people know, that viruses are completely different system when compared to cellular life. The common ancestor concept can’t be applied to viruses…. moreover, most viruses are unique – it is like to explain the origin of life thousands of times over and over 🙂
p.s.
this is brand new (OCTOBER 2019)
‘Strange New Virus Could Represent ‘Entirely New System of Viral Evolution’
“…a new type of virus that could challenge the already complicated notions of how we categorise what viruses are, and what they can do.” 🙂 🙂 🙂
https://www.sciencealert.com/mysterious-new-virus-could-represent-entirely-new-system-of-viral-evolution