I don’t assume the US stock market is inherently different from the Japanese stock market.The main difference being the bigger the bubble the deeper the collapse. No doubt Japanese pundits could point to past short bear markets too.
And if you go by US experience alone, the present bull market is old, not dead yet but maybe ready for Medicare.
Though I don’t think US stock markets cheap they may not be that much over priced either. Because the world, and the US in particular, is safer than it has been in much of the past. Present potential peace/prosperity disrupters are not in the same league as Hitler and Stalin. And because the prime alternative investments such as real estate and bonds don’t offer lots of competition.
I will make no attempt to forecast the timing of the end to the bull market because as you point out, generalities are mostly non actionable. But I will forecast with confidence that it will end. Eventually.