Idea Summary
Now we have plugins for implementing components that might be reused and subscribed between applications, but it requires PL/SQL, javascript etc. I do miss a lot some way to do exactly this but partially with no-code. Now we have Applications, Pages, Regions and items. But you cannot design a “Component” that might be composed of regions and items, and reuse it in lots of places. So when you have to change it, you just change it in one place. The only way to do this right now, is either with plugins which are not that easy to build, or just calling a modal dialog in another application. Something like sharing the header and items inside it, or the footer between multiple applications is something difficult to do.

Use Case
Simplify developer experience and repetitive work by allowing to design centralized components.

Preferred Solution (Optional)
Graphical component designer that could be the same as page designer, that allows to build embeddable components in other pages. You would be able to create a component in a centralized application, and subscribe it from others. Like plugins do, but in a native apex way.