Not that it matters much, but with the latest 70%-70% the projection is November 27th.
It could be even before that if it starts to get the pace he had at the beginning of August (Nathalie and Dylan's events) and the remaining Sam's event and Cathy's event are not too time consuming for the scene creation.
But who knows, these are mere academic speculations...
December seems still a safe bet
Yes you are right, that's exactly what he said here
We don't know if it will be a family event, from what he says it is centered on Sophia and Patricia.
And, again, without any evidence to support it, it's really hard to see how long or how complex it will be.
It can be a relatively short event (wrt the time span in which it occurs), centered only on Sophia and Patricia and, beside the main event between them, he may quickly gloss over the rest of the trip and move to the next event of the day (which is still unknown).
Mutatis mutandis, it could be a sort of Sam concert.
Or as you said it could be a tough one, where even new characters are introduced, new side stories etc. That, on one hand could be interesting because it offers many possibilities, on the other it will take more than one release to finish. And again new characters, new assets.... And/or, like Sam's concert, he could decide to move it to DLC.
Personally, I would more concern about all these DLCs than the ranch event as a sign of loss of interest. We all know that, realistically, these DLCs will never be made, unless he decides to abandon the game and give a final eye candy to the patrons.
Not that I'm against DLC, especially if they could be used to trim side stories and reduce the number of non essential events. And, ***in a ideal world***, DLC could be the perfect way for him to delegate part of the game to someone else. He can "train" someone to get small things done with his quality standard without the pressure of the game main release. And then with time she/he can help him later with the main game. But, obviously, we all know it's not gonna happen.