I've explained my views on Snapchat before (synopsis: It's a great way to communicate casually, without fear of permanence.) I don't think it will ever become "the standard messaging app."
Kik fills the role outlined in the article already, minus the status update (story) shoe-horned in. It also has the benefit of already being a lot of people's standard messaging app. The real difference is in permanence, where Snapchat fills the role of disposable messages, Kik fills in with semi-permanence. Kik also takes on the idea of being a platform, where many apps are designed as an extension of Kik, to fill in the need for meeting strangers, playing games, etc.
The downfall, in my opinion, of Snapchat is, and will continue to be, Snapcash. It's basically a way to become an adult cam-site, without blatantly admitting it. This increases spamming and scamming, from both people and bots, reducing user enjoyment.
Snapchat has it's specific niche (disposable media messaging,) but almost all added features seem supplemental, and simply seem like it's trying to keep up with other forms of social media. If Snapchat is going to stay around, it needs to emphasize privacy, usability, and the original ideas it was based on. Otherwise, other apps are going to win out.