Customize users list in autocomplete tagging system for adding users to threads

Problem/Motivation

It would be great to be able to customize the aspect of users in the autocomplete tagging system for adding users to threads.
For exemple, it would be interesting to be able to show the avatar of user.
Users lists are customizable in thread members. It would be nice to be able to do the same in this autocomplete module.

Steps to reproduce

You just have to create a new thread and see how users list is shown. (see screenshot)

Proposed resolution

Add settings to be able to customized users in the automplete module.

User interface changes

Be able to set an autocomplete module like in Facebook (see screenshot).