We could have a privacy-oriented chat platform with a cryptocurrency "small cash" type of transaction system built on top. Combined with some informal craigslist style mini-stores, which flourished in China via Wechat.
I'm sure FB/WhatsApp could do it via normal payment channels, probably involving Visa/Mastercard. But the privacy story is awful for such a critical piece of software. Assuming they could pull it off. Maybe Kik could take up the privacy flag?
WSJ made a nice video of how Chinese people live "cashless" via WeChat in Shenzen: https://www.youtube.com/watch?v=75AXINUL47g
Granted, if Kik went bust tomorrow those tokens would most likely have no value, since their use is tied to Kik's messenger app. But in theory you would still own the tokens and could transfer them to anyone who would accept them.
I feel like most services that aim to replace another one ... just want that information for their own purposes, not the customer's benefit.