@chris_parjaszewski I just wouldn't call anything other than Swift & Objective-C a native technology. Yes, React Native and Xamarin are more "native" than PhoneGap in the sense that they bridge to native components instead of just being a wrapped web app, but they're still wrappers as nor JavaScript, nor C# are officially endorsed by apple, meaning Facebook and Microsoft have to wrap around the new APIs first and thus are always behind. Try writing an iOS 10 app in React Native today and you're likely to find that support for new APIs announced at WWDC is not yet there.
The app is also likely to run slower, simply because of the overhead that the glue code to bridge components, (i.e. the compiled code is unlikely to be idiomatic), incurs and for a complex app with possibly hundreds of classes, you usually can't afford it if you care about user experience
But most importantly, if it's a complex app of any sort, there will be time when you have to drop down to Swift/Obj-C because the React Native/Xamarin solution won't be up to pair, (so it doesn't even have the befit of being end-to-end in JS), and if you need help, everyone is going to assume Swift/Obj-C as a baseline, which will make things even more difficult.
Even Facebook's own app isn't built with React Native.