This is me writing down my wishes (and dreams) for version 4.0 and I hope I won't hurt anyone in doing so because I'm a rather drastic person...

As always, I'd love your ideas too. I'll edit this post if something else comes into my mind.

python

• get rid of python 2.7
• fully asyncio based
• minimal version of python = 3.6

drop the formatter

• use python f-strings formatting only

seamless configuration updates

• configuration reader should backup and update user config on the fly
• allows faster / easier deprecation of config etc
• reports on a special file to user inspection (and auto backups as mentioned earlier)
• would be auto by default, with ask-me-first or never options

make i3status a module like any other

• would be launched seamlessly if config use a i3status module
• but would be removed from core

usage tracking (opt-out by default)

• allow users to share their usage and love of py3status
• provided as a module with no output

make thresholds & borders general options

• in the core

implement a dbus event handler for modules

• already worked on WIP: dbus helper for modules #1547 so it should be rather easy

add default short_text support

• can be overridden per module
• reference PR : core: add short_text support [wip] #1494