Thanks you for keeping us informed. I'm very interested by the other feature ideas too.
I have a few questions regarding the mock-up with the ToC proposal though. Wouldn't it make harder to implement later specific options for media/figures and tables types of Table of Contents?
I also came up with a few suggestions for improving the "permanent" ToC idea:
- OOUI icon for ToC added around the "Title+section" title group, looking like the one used for the Wikipedia app on Android
- Expanded ToC column located at the opposite side of the toolbar (apologies for mistakes in the original post; my pc had a very annoying bug that forced me to publish a draft before a complete reboot)