There was some discussion here on this topic: Brainstorm: Library sharing - #5 by zef
Ultimately I decided to go with the simplest viable solution and see how it would work out for people. That is: just override all templates on every library update, and let people exclude specific templates and maintain their own copies. We can do fancier things like filters, overlays and other stuff and maybe we will at some point as this functionality is more heavily used. It does add complexity, and in places it’s already hard to understand why different things do or do not happen. Adding more complexity would only make that worse. We’d need a debugger tool of some sort 