Edit spelling
The other side of that is software that already exists, running in the background unnoticed. Things like your graphics driver. You wouldn't want that written in Java. If it were written in Java you might get a lot of features faster, but it sure would perform like crap. For core software like that, development costs are secondary. Performance matters first.
At the end of the day I think we need projects like neovim and oni. Editors are old technology and should be core software. Performance in my editor matters. I have five different IDEs installed and I still use vim.
The hell are you talking about, Electron still doesn't come near the marketshare when you look at acual apps using other cross-platform GUI toolkits.
Another bit seems to be some work in progress from the Xamarin guys at MS.
In the end, an XML based UI combined with a JS runtime engine seems to be a very powerful combination... getting similar points of integration with other languages could be equally nice.
Something resembling Material Design, or Bootstrap as a cross platform UI toolkit with an XML interface would be a great place to start. Electron really seems to be as close as it gets for the most part, with the least cross platform effort.