One thing I really love about Musing is its minimalistic and simplistic UI and I hope that they won't overdo the future changes they are planning for the site as I am pretty much content about it at the moment.
I however would like to see Musing have an option for a "Night-Mode" or dark-theme. As someone who has somewhat a sensitive eyes, the white background on Musing.io is sometimes just too bright.
And if you consider these a feature, it really would be good if they can release a mobile app before the year ends. A mobile app with a "night-mode" feature would be more than perfect. :)