I doubt Kaine would suddenly move back to NYC from Houston and take up Peter's costume. He's too focused on learning what it means to be his own person. Being Spider-Man, rather than the Scarlet Spider, would be a step backwards for him.
In any event, if this were any other writer, I'd probably be concerned. But this is Dan Slott, who has been doing amazing (yes, pun intended) work on the character during his run. I'm so happy with Slott's work that his Spidey title is the one Marvel book that I'm keeping as my current financial situation warrants the dropping of pretty much everything I've been reading for the past few months. It's been too good for me to consider leaving it.