Fair point, for text it is far harder to prevent signatures being applied to generated text vs images at the moment of capture and most approaches I can come up with to remedy this can either be bypassed (edit histories can be output by models similar to humans) or will be controversial. Taking a page out of the anti-cheat textbook, mainly written for gaming, there are methods which might hold in the medium term. Less a fan of kernel level myself, though it might be worth exploring as there has been massive investment by the games industry into making it somewhat robust, but the approach Valve has taken with VACnet could be an inspiration worth exploring that is less invasive into peoples systems. Keystroke analysis, etc. could be relied upon as a basis for signatures, harder to spoof for current day LLMs over generating edit histories.

I will fully admit that at a point in the future, maybe not too soon, models may be trained to bypass that too, at which point we are back where we started. As a skeptic of the extend that capabilities are emergent in LLMs vs specific to training data, I am somewhat hopeful that unless models are specifically trained for evading such human detection solutions, they'd struggle to do so, but it could still end up as a byproduct of improved, lower latency computer use focused training. Not emergent as the term is used in regard to models because that is still output performance improvements clearly traceable to very specific training data, but incidental as the goal of said training data was not to bypass.

For what it's worth, I find human authorship being verifiable to simply be the more crucial problem over watermarking model output, so if research is to focus on one, I'd rather it the former. Maybe both signing human authored content and watermarking LLM output are both only possible in the near term, I hope not but fear it that might be the case. If so, we as a society will have some major challenges ahead (beyond all the ones we'd have anyways).

Alternatively, we could also just start scanning everyones eyeballs...