Sometimes I make master components with icon placeholders / image placeholders.
When I make instances of those in my designs, I cannot change the icon out without detaching the instance from the master component. (There is a tedious workaround, which is to include lots of different hidden icon layers in the placeholder spot in the master component)
Instead it would be wonderful if there was a new feature in Figma such as a “placeholder icon” and “placeholder image” (or just a global “placeholder element” which could accept icons, images, etc) which could be used in components. Then any instances of the component could have the placeholder easily and manually replaced in that particular instance / design via the editing area or layers panel.