I would like to see the following directions included for Squeak:

Modularity and minimal core - so that you can load what you want onto a minimal core and be sure that you can unload the same thing cleanly. If a newly loaded package provides a new version of a method when the existing version is absolutely required by another existing package, allow the previous version to remain usable alongside the new. This should all be done in such a manner as to hopefully minimize the need for forking, or think of all custom images as forks like Guilik just mentioned.

Along with the modularity, a convenient system of automatically loading your custom modifications, such as: 

Automatic test and build server eg. Installer, 'Sake/Packages' and 'Bob the Builder'.

Simple method of logging your ongoing work and migrating all your current image state to a fresh image.

Remove the barriers to using the latest dev tools like MC and ensure various updates get merged into the externally managed and loadable/unloadable package.

Remove the barriers to loading/unloading things like Tweak, Sophie, EToys.

Good code execution visualization tool to help understand the way things work. 

A bug/enhancement tracking system that people like to use.

   Ken G. Brown