Tags, more powerful for forums

[kmk]

An idea that I am not sure if possible. How about if we can assign permissions for use of tags, then in a forum members depend on tags permission will can see or not the topic? 

With this system we can avoid create so many forums by categories or type of contents.

The tags will help to classification of type or categories need. 

Before IPS staff consider to add this feature to the core, @Makoto you can do something with your tag app?