Yes, I've posted about this a few times - but it is too big of a project and not novel enough to get many skilled engineers interested, I think:
We need a Zoho-like replacement for Google Apps that is open source, and has a host-agnostic ecosystem around it. Someone should be able to launch the apps in their own docker containers, with a button click on AWS, and evolve features like protonail et al.
Not all of Google's apps need replacing, but it should include custom DNS, calendars, collaborative editing of documents, email, browser-syncing, storage, and possibly even a mobile data management and decentralized chat! Who wants to start building a team to work on it? :)