I think this points to the only real sustainable solution: make it so that students would prefer to do real work. We have seen for ages the distinction between seeming and being in regards to verbal understanding blurred. LLMs are only an acceleration of the blurring. Therefore it will at some point become essentially impossible to determine whether one really understands something.
The two solutions to this are (1) as some commenters here are suggesting, give up entirely and focus only on quality of output, or (2) teach students to care about being more than appearance. Make students want to write essays. It is for their personal edification and intellectual flourishing. The benefits of this far surpass output.
Obviously this is an enormously difficult task, but let us not suppose it an unworthy one.
Or you just make in person exams the majority of the work and make the exams brutal. If you can't pass the exams you don't pass the class, so you need to learn enough to pass the exams.
The two solutions to this are (1) as some commenters here are suggesting, give up entirely and focus only on quality of output, or (2) teach students to care about being more than appearance. Make students want to write essays. It is for their personal edification and intellectual flourishing. The benefits of this far surpass output.
Obviously this is an enormously difficult task, but let us not suppose it an unworthy one.