You're not worried about performance issues and lack of features? Are you running into any issues with app approval with Apple?
A few years ago I decided to start building all mobile apps using native languages (Java, Objective-C and Swift). There were too many performance issues and limitations with the RAD tools. Now Apple is considering denying apps that are not native due to the performance problems. I've not tried Xamarin but I know people have used it and didn't have issues submitting their apps with it.
HTML has come a long way and the current plans for the future HTML look promising, but I don't see how it can keep up with all of the changes Apple and Google release to their OS every year. For example, SceneKit and MetalKit from Apple take animations to a whole new level with performance just as good as OpenGL. Harnessing those frameworks through a proxy RAD tool from Telerik and Xamarin has got to add performance problems and issues you would not normally have if you developed native.
Another example, the Syrup app for Hotcakes uses the Apple Core Animations framework. It could have been done with HTML, but with an extreme performance hit. So much that I doubt Apple would approve the app for the store. You can see these animations in the demo video at https://www.youtube.com/watch?v=UNsMe...
In regards to the future, I have serious doubts we will be walking around with the phones we know today in 2020. There are products hitting the market soon that project the screen of the phones to your arm and it uses augmented reality to let the user interact with the projected laser screen. I'm sure HTML based apps will still apply but I have serious doubts they will be able to harness the device and OS features as it progresses into the holographic features Microsoft, Google, Sony and Apple are planning. See http://www.microsoft.com/microsoft-ho...
I also found web services integration between the apps and DNN much easier when coded using the native language.
But you are 100% right about speed of delivery. Building native means having the resources with the skills to build for each platform and then maintaining multiple code bases. I have thought about using C++ to help with that since C++ classes will run on both Android and iOS native. However, C++ requires a lot more code than Java and Objective-C.
In summary, using the RAD tools give you faster delivery but with a quality cost. If Microsoft can close that gap with Open Source C# on Android and iOS then all of the above may change as long as the performance issues they are having now can be resolved, otherwise it's the same as any other proxy framework.
What are your thoughts on the above?