the feature Composite Step Templates has started which should meet most of these requirements. The underlying templates will still be linked so that they can be updated as per normal step templates.Brian Herbert commented
You will find a nice diagram to illustrate this suggestion if you look here:
http://help.octopusdeploy.com/discussions/questions/10468-run-a-step-after-every-deployment#comment_41799080Brian Herbert commented
This is not really a template because you want to "keep the reference". It should be called Inheritable Projects.