I'm not entirely convinced the polling is properly representative of anything but Republican sentiment, as the last NYC poll I read claimed that, but it had been compiled before the indictment, with a significant oversampling of Republicans (can track it down if you'd like - it's back in my commentary someplace).
I think there's a narrative being pushed that inflates his popular support, as Biden would blowout any of the primary contenders in this political environment. This is a negative for media companies, that thrive on engagement, and rely on a down to the wire political circus to keep their engagement numbers up and ad revenue flowing. Inflating Trump has been good for them in the past, and I'm not surprised to see the trend continue. This isn't an argument for complacency, but I think that the political calculus in play is telling.
It's clear Trump is imploding and his big money supporters (all members of the GOP establishment crowd, not the Tea Party for the most part) have abandoned him - not because of the indictment, but because he blows through money like water, and has already cost Murdoch close to a billion. He needs that money and influence to protect him from within the government establishment, but he's burnt those bridges, especially in GA, where he cost them a Senate seat and dragged Raffensperger through the mud.... the same official who not only provided evidence against him for the indictment, but who will be deciding whether or not Trump is disqualified to be on the ballot under the 14th Amendment.
Thus far, Raffensperger has shown himself to have not only a spine, but integrity and a respect for the law. We'll see how strong that spine is when Trump tries to get on the ballot in GA.
I believe, as you do, Raffensperger has every reason to throw Trump under the bus, as does Kemp and the entire GA GOP good ole boy establishment, and the GOP establishment across the country knows that it would be good for the party and their financial interests. They know he won't win against Biden unless the economy tanks completely, and that's unlikely to happen before the election.
If the GOP establishment kneecaps Trump now, that gives time for the primary field to clear and for a real challenger to Biden to emerge. The longer they wait, the more likely they'll end up with another loss on their hands, one that will likely cost them the house as well.