Lotus Notes didn't have video, and sound or real-time chat functionality. It does integrate a spreadsheet, decent word processor, calendar and task list. Google Docs with its Calendar and Gmail integration is close enough.

Integrating different use cases is different from interoperability. For example, make it easy to share a file on drive via email and chat does not require drive to be integrated. Likewise meet (new contacts, social net) vs chat (known contacts, rooms) might be a good split if they interact nicely together.

Splitting chat from email is a stretch, much like with voice from text or from video. Or simple images.

What Google is doing is create apps that do not work together with each other.