FWIW there is a hint of data out now: the difference in the HarrisX polling results from 7/29 - 31 and 7/30 - 8/1 (most easily appreciated in the 538 poll tracker).
The difference of moving the 3 day result window into one that included a day after the second debate was … (drumroll) … Biden staying stable with Sanders losing 1%, Warren gaining 1%, and Harris not moving. Next rung Buttigieg dropped 1 and Booker gained 1%. Note this is one day of post debate polling out of three move of the needle. So yeah so far my prediction that
is not so off. Harris didn’t drop (so far) but otherwise on the money. (Go me!) Let’s see what more polling brings!