"Of course, at some point your ability to build ever bigger particle colliders will fail, so you can never verify that you have The Final Theory of Everything."
While true of purpose-built accelerators, there are other ways to access higher energies -- the universe itself is a low luminosity 10^10 GeV accelerator accessible by data-mining cosmic ray events. That gets us most of the way (logarithmically) to the Planck scale. We'd just have to change our idea of experiments from contemporaneous groups to a "generation ship" model.
And that could be a good way to think about empirical economics -- we've only had a few decades of decent macro data. Maybe we need to wait it out a few more decades before we can draw any macro conclusions ...
[And now it's gone ... and I have no idea why ...]