My point with the observation you quoted wasn’t “This would be unprecedented, therefore there’s a very low prior probability.” It was more like: “It’s very hard to justify >90% confidence on anything without some strong base rate to go off of. In this case, we have no base rate to go off of; we’re pretty wildly guessing.” I agree something weird has to happen fairly “soon” by zoomed-out historical standards, but there are many possible candidates for what the weird thing is (I also endorse dsj’s comment below).
My point with the observation you quoted wasn’t “This would be unprecedented, therefore there’s a very low prior probability.” It was more like: “It’s very hard to justify >90% confidence on anything without some strong base rate to go off of. In this case, we have no base rate to go off of; we’re pretty wildly guessing.” I agree something weird has to happen fairly “soon” by zoomed-out historical standards, but there are many possible candidates for what the weird thing is (I also endorse dsj’s comment below).