Allow nesting component instances into the same instances (not directly)

Intro

There is an interesting concept in Figma that’s used and was presented by multiple people and has different names: Placeholder, Slots, Dummies, Layout Blocks, and so on:

1. ❖ Placeholder component is the base one.
2. ◇ Placeholder instances may be nested into another ❖ Component.
3. ◇ Placeholder instances nested into ◇ Component instances may be swapped with any other component instances…
   More details in this video by @Adam_Ruthendorf-Przewoski.
   The next step of its evolution is Layout Blocks by @Mr.Biscuit.

An issue

1. I have a base ❖ Placeholder component:
   
2. ◇ Placeholder instances may be nested into other components (❖ Column here):
   
   
3. What I need is to nest a ◇ Column instance into another ◇ Column instance by swapping one of the ◇ Placeholders.
   This is needed to customize Auto Layout spacings and other properties:
   
   
4. But when I try to do this I see an error message Failed to set component: cycle detected!:
   

I totally understand why we’re not allowed to nest instances into their Main components — it will create an endless cycle such as infinite screen share:

But actually, it is not endless — we always will have the last one ◇ Placeholder instance as a stop point:

My Demo file to better understand what’s going on.

Possible solutions

There are a couple of solutions that solve this issue but still are not optimal:

1. Have multiple absolutely identical components to nest one into another.
   
   
2. For the upper-level use a component with more placeholders inside and hide unnecessary ones.