In principle - if you're able to scale appropriately, using technology to augment capacity, then in principle, there's no abstraction for which we lack the capacity to comprehend, because calculation is calculation. Turing Computers can calculate anything which can be calculated given enough time and memory. Brains are Turing complete.

It's not just a tautology, it's a feature of the universe- if it can be computed, it's comprehensible. Even quantum physics is just computation - truth tables and counterintuitive operators interacting over time in ways that are strange to our embodied norms, but nonetheless following rules and limits strictly defined by mathematics.

But again, that's in principle. It might be completely impractical - taking a million years for an individual human - to hold a particular idea in their head, while an advanced AI can have such thoughts many times a day. Such things would remain mysteries, but in principle, an augmented human, or a series of interfaces with the relevant abstraction levels of such an idea, theory, or system, would in principle give us comprehension.

In practice, we'll never run out of mystery or ignorance or mistakes.

It could potentially be falsified by an encounter with really weird aliens.

But I find it quite plausible because it feels like it's fundamentally "just" a restatement or a minor variation of the Church-Turing thesis.