This post reference Apache Royale many times and I use AIR only for Apps (not games) and Flex for many years now.
I started with AIR + FB 2 or 3 (latter 4.7) from the beginning and on that time my thoughts was that Flash will disappear (unfortunately, I was not wrong).
HTML5 became famous and FB it's clear as crystal ball that it's abandonware.
It took me 1 week to use IntelliJ (version 14 on that time) until today (the first tool from Adobe that I left).
Later, I needed a Web interface (it's a very simple use case and it's not the main UI), so I did it with pure HTML5/JS (the only addition was basically jQuery). You may think that I'm crazy but I'm not depending on a fancy JS library that it's like a Fenix (born and die) and it's work very, very well for me.
Later, I needed a Mobile interface (so a specific module of the main application) but I had only 2 about weeks to implement it (it was 2 years ago) and AIR it was entering on pure maintenance mode, despite of other people may argue (and I'm being nice), so I built that Mobile AIR in a record time.
I need now a second edition of my App with a complete new UI a much more features and time.
I was planing this for a long time and I started recently with Xamarin (again, a get rid of Adobe on Mobile for good).
The missing puzzle for me it's AIR on Desktop and ironically it's the must difficult one, on contrary to most developers that use for mobile.
I already evaluate Apache Royale (it's in a alpha release for years).
Basically, I felt that I cannot ask anything to does guys that someone will thru a stone, always with the same story "you can do your self and donate the code to Apache Flex".
HTML5 it's for websites and not to mobile or desktop Apps.
.NET don't have nothing to Windows and non-Windows UI (perhaps in the future).
Recently, I checked Haxe/OpenFl and I got a very good felling about it but then I saw that the gap of XML UI and it's and issue that completely void this option.
Then, I saw this post.
I can help more, with paying a fee, than donate code (perhaps I would even take time of the author, with issues) and for what I have seen so far, if there someone can do it is the author of Feathers UI (I hope, I'm correct for my own good).
Apache Royale have few guys and probably too much good to listen dummies (not all).