Historically Bitcoin tends to pump in Q4, which often leads to alts bleeding. With BTC so close to setting a new ATH and going into price discovery, this looks likely again. I wouldn't expect (most) alts to make substantial moves until after BTC dominance peaks and there is a trend reversal.
I think that this will not happen precisely because everyone thinks that btc should do as it always did. Of course, someday it will start to fall, but I think not soon.