There are some fairly strong signs that Trump has lost about 5-10% of his previous support and that depending on new low propensity voters to turn out for him is a losing strategy.
Hundreds of defectors against Trump in the republican party, including many of his former cabinet members and traditional conservatives who love America, have created a permission structure for mainstream republican voters to not only not vote but also to cross over to vote for Harris.
This, and Trump's meltdown late in the race, has created momentum against him and for Harris.
Take out the trash partisan polls and Harris looks solid.
Pay close attention to some of the underlying numbers, like Harris winning the 65+ crowd and senior women >2:1 and independent women by large margins and Latinos by large margin and retaining support of Black voters near historic levels, and I think it spells doom for Trump's chances and victory for Harris.
And I don't think it's as close as trash partisan polls might make you think.
If Selzer is as spot on as in previous presidential races then Harris wins 7/7 battleground states and Florida, Texas, Iowa, and Ohio are in play. The House turns blue and the Senate does not change hands. IOW, if Selzer is right it's a true blue wave.
Anything can happen and it all comes down to turnout.
ETA: And Harris has a huge advantage in GOTV efforts.