Thanks, this is exactly what we're doing. The complete scope is detailed on https://about.gitlab.com/direction/#scope

By the way, we see Mattermost as an alternative for Slack but not for Gitter. One is team chat and the other is 'project' chat with different requirements.

It does , because this is one platform with fully inter operable work item, build number, change set id , deployment server integration readily available , if you notice the individual tools, they come from different org's and have different way of working , except that they have a rest API exposed for you to integrate any other tool in a limited way. Its like when a developer makes one line of code change , he or she can use this platform to shepherd the change into production in a fully automated manner and take responsibility for the same.