And who didn't see the whole HRG "Wife" turning into that black haired b*tch? Saw that one comin amile away...
The moment he realized his partner's new power, he should have asked his wife a very personal question; once she answers correctly, then they can come up with a password (which he'd have to really hide in case Parkman was nearby).
So is Isaac going to survive the story arc?
I doubt it. But they said the next death would be unexpected, and it doesn't get much more expected than that. I'm not even very attached to Isaac as a character, but when he painted the picture of himself dying, I found it to be a very sad scene. His paintings and comics are really cool, so it seems they will come to an end unless Peter can take over. Isaac's final painting ...