Of course, you can try to push it in the direction of something more interesting... "write in the style of X" so that it will regurgitate from a subsection of its training input, or push it onto a niche topic. Across a wide range of inputs, though, I predict it will be easily classified.
As training GPT will take far longer than training a GPT-detector, this is an arms race that the detectors will win for the most part. Anyone wishing to use GPT to generate middling essays to cheat at school will have to spend a lot of time to disguise the text (perhaps repeatedly running against open-source detectors) and then take the risk that detection does not improve between their submission and review.