Standardised plugin mechanism1 user found helpful
Yesterday Franz spoke of pluggable checkout modules for 5.7 commerce. We already have many addons in the 5.7 marketplace that accept pluggable extensions (and many more in 5.6, many of my own addons use my own plugin management mechanism). Some of these systems are fairly primitive. Others are quite sophisticated. All are different.
Every developer of plugin-extendable addons has created their own plugin management system, where their addons can discover addon compatible plugins, manage them, and use them.
With so many things being pluggable, there is a big opportunity for the 5.7 core to include a standardised plugin mechanism, so that anyone creating a package with further pluggable extensions can use the core to discover plugins for that application, manage them and use them.