Never resign. Politics 101.
Empathetic take: her opponent already started campaigning against her with this, so I doubt she'd want to relive it.
Standard take: the internal polling looks bad and the ethics investigation isn't going as well as she may have hoped.
Exactly. The Virginia Governor and Lt. Governor still haven't resigned after their accusations earlier this year.
Stay the course...
Not the same thing.
She hasn't been in office for a year and she's up for re-election in 2020. She'd probably lose reelection anyway because she's not some long-tenured who is beloved by her constituents.
Northam's term ends in 2022. The domino effect this has would result in a Republican becoming governor, so there's a different dynamic at play. IIRC, VA governors can't serve consecutive terms so Northam couldn't be on the next ticket anyway.