According to "A person familiar with the matter", website CVG is reporting that, as part of Microsoft's continuing efforts to consolidate Skype (which it now owns) as the standard communications platform for the company's products, it'll "become the default chat service on the next generation Xbox console".
What would this mean, exactly? Who knows, the report doesn't go into much more detail than that. But what it could mean is that everyone using the next Xbox online would need to tie a Skype account to their gamertag (Windows 8, for example, already ties a Microsoft account to a Skype account). You'd also expect some form of Skype branding to exist for the console's communications, rather than the more vague "messaging" terms used now.
One thing the source does say that's interesting, though, is "You might jump to the conclusion that we'll see asynchronous voice and video messages in next-gen Xbox Live". Which would be pretty neat.
We've contacted Microsoft for comment and will update if we hear back.