>> it's considerably harder to customize native controls than it is to customize or build custom HTML controls. Usually the only effective way is either to have hotshot designer on your team, or you buy third party control suites. Considerably less flexibility. The bar of entry is a lot higher with native IMHO, and while I think for consumer facing applications an App may be a requirement, for business facing applications I think it's questionable that the overhead of creating and publishing native apps provides additional value over an HTML based application.

There's no reason I can see for a local app not to create FiC-style HTML5 or Bootstrap or whatever to be displayed by the device's native display mechanism. IOW not trying to reinvent UI wheels on every platform, and everything true of FiC can remain true except hooking events and comms back locally rather than via AJAX or whatever to server. That's already fairly easy using VFP's Web Browser control, so hopefully not too difficult across a few other platforms- and certainly less dismaying than reinventing UI wheels which, as you note, would be a huge hurdle.