I'm about as upset about the Z4v as anyone, but I'm really skeptical that the Boot Loader issue is the whole issue and I suspect that Sony has as much of a hand in it's cancellation as Verizon.
If the phone had launched on Aug. 13, there wouldn't have been much an issue--it gets on the shelves before Z5 is announced and 6s is released. Sep. 3 put it too close to both of these. An Oct. release is strategically even worse--Z4v just becoming available in the US while the Z5 is available internationally doesn't help Sony's reputation.
So assume the whispers of Z5V in November are correct--the phone hits the market in time for Christmas, later than international launch but giving a chance for people to realize how good its camera is (check) and that the SD810 issues have been resolved (maybe check?). Sony them makes as good of a reentry into the US market as could be hoped.
Early November may make more sense than late November (tie in with Spectre release for marketing). That all said, I'm still angry at Verizon for their poor handling of the situation and stuck with a barely functional phone in the meantime. If the opportunity to get a Z5 for another network comes up this year I'll take it.