I've asked this on other threads (but no one has answered), but what's in it for New Balance? They already have a long list of attractive female American runners who are at the top of the sport and active in outreach/public appearances. They also have great shoes. And they have Heidi Klum and Disney making the product more enticing to what many have described as the typical Kara fan (I mean how many reboots of the 890 V3 have there been?). And honestly, I think having great shoes in cool colors is going to pull more recreational runners to New Balance than any individual athlete.
I do get that Kara has a lot more followers than any of the current NB athletes, but if I were NB I'd wonder if it was worth it to hope to rebrand an athlete who admittedly near the end of her career (particularly when I think we all are in agreement that Kara is asking for what would be one of NB's largest contracts). I could see them wanting an American marathoner . . . but Kara doesn't want to run a marathon for a while. Regardless of her potential, not making it to Worlds in the 10,000m can't help her case.