Reading through the article, the author seems to be hoping for a pure GUI approach with Emacs-like navigation mechanisms, but I am not convinced that this can be as flexible as text-based widgets. However, for packages used exclusively within a GUI environment (like el-easydraw [1], which relies quite heavily on SVG-based widgets), it would be nice to have a dedicated GUI widget library.
(There was a discussion on Reddit about this a week ago [2], and I saw some comments defending GTK and PGTK that might be worth reading.)
[1] https://github.com/misohena/el-easydraw/
[2] https://www.reddit.com/r/emacs/comments/1kcgwme/the_emacs_wi...