Just the simple functionality offered by the Bolt application will ensure its success against Snapchat. The ability to actually talk to someone, anyone, without incurring additional costs is very appealing to value conscious young people. Snapchat is very limited in its offering to a worldwide user base. Bolt could be the next killer app.
Look at the Comparison between Myspace and Face book, these two sites were very good sites to be on to chat with your friends, but then Face book took that market, and now they are dominating on top of the charts, along with twitter, there will always be a new takeover regarding these new Apps that are being built.
Bolt is popular in some countries, but it has not proven that it will last or take Snapchat's spot. Additionally, some reviews of the app have not been positive. It has flaws that make it less likely to take Snapchat's spot. It is also not overly unique and not a lot different from Snapchat, thus dissuading consumers to switch platforms.
I do not think that Bolt will overtake Snapchat when it moves into a worldwide market. Sometimes it's not about which app is better, it's about which app makes it to the market first. Snapchat has the benefit of being used earlier and being more popular by the general market.