"He wasn't talking to anyone anymore, just her."
I've decided John became attached to Cameron in the future because he was depressed about having sent Kyle away on his one-way mission to
From a timeline standpoint, I think it fits. Based on what Perry told Derek in D&D, reprogrammed machines were already being used by the Resistance by the time Kyle left. So all the reprogramming started in between Derek getting nabbed and Kyle time jumping. Since the show implies that it was Cameron who interrogated Derek in the creepy basement, Allison would've already been dead by then and her bracelet in Cam's possession. Once she got the location of the bunker from Derek, she would've been on her way to infiltrate and kill John.