What your customer desires is a product dedicated to "FORUMS." Please do not add social groups, blogs, and other CMS programs that ruin the experience of what forums are all about...meeting people of the same interest to discuss a "specific topic." It's difficult enough to generate activity and post on new or even old forums. Having these extra features deters forum activities and turn off many potential users from joining or posting due to being bombarded with features that they will most likely never use and unfamiliar with.
I'm not saying we should not have the above stated features. I'm saying you should make that a separate product. Dedicate your time to develop a clean and amazing "forum" software. Make it as user friendly as possible. Leave the development of plugins to other developers.