I’d like to try to group the extension and who is needing them.
For my use-case, add markdown support to sphynx, I need a good deal of editorial support (e.g. include, attributes, yaml-extradata and few more) that probably can be implemented by adding the IAL support kramdown has or something similar, on top of it tables are of interest and maybe the math support.
I’m sure @vitaly knows more use-cases since he has a fairly large collection of plugins.