I don't see CocoonJS as a "phonegap killer", maybe a "phonegap build killer", they've just added cordova/phonegap API support. They've created an improved webview for iOS and android, but phonegap isn't about the webview, is about the API over it. Sad part is they aren't open source, but they did a great job with their webview.
Anyway, after iOS 8 and android L with their new webviews, maybe this kind of projects (cocoonjs, crosswalk) won't make much sense in the future
