There are some efforts on the design side though to come up with a
replacement for menu bars (think "menu button" in Firefox/Chromium).
See https://live.gnome.org/Design/Whiteboards/Menus for reference.
Wow, the mega menus really do look great. I would like to have something like that on the titlebar, open it by pressing Alt, open it on a specific column by pressing Alt+key. Same functionality we have today, without the wasted space and the bad looks.