I would be very surprised if they abandoned Peggy entirely, but her growth this season was sort of limited. As usual on this show, it's the most natural path for her character to take. I'd love to see her compete with someone at SCDP later in the show.
It's also interesting to note that Joan ONLY hugged Lane once they got Jaguar. I don't think they're setting Don and Joan up for the long game. Just because they're both the epitome of sexiness in their respective genders doesn't mean they'd make a good pair. Her chemistry with Roger is a lot more palpable.