Azure - predict the instance that the fabric controller is going to shutdown when reducing instance count

Currently there is no way for a developer to shutdown an particular instance - see link to thread below. The only way is through changing the instance count in the service configuration file - either manually or programatically. Therefore I ask myself - the fabric controller picks the instance depending on a certain pattern, probably in most cases the instance with the highest instance index and in some cases, if it violates the rules given by the upgrade domain or fault domain, another instance.

Has anybody found out the pattern that the fabric controller is following?

I talked with development support of Azure, they told me that this feature is currently not available. The pattern valid is that in an ideal situation (no hardware failture, app failture, etc) the instance with the highest index suffix will be taken out. The inner workings of the fabric controller rely on multiple (hidden) factors and are hidden from public due to confidentiality (what a pitty). As you proposed I entered an idea, knowing that this is currently and  in the near future this is not possible.