Presumably, the same functionality will be rolled out on Switch, iOS and Android, with social systems (friends lists, messages etc.), multiplayer and achievements to be integrated, expanding the userbase for Xbox Live in the process. The listing said Xbox Live users are already engaged on Microsoft's Xbox and PC platforms and listed achievements, friends lists, and clubs among other features as the perks of having Xbox Live support on non-Windows devices.
What's different here is that Microsoft is extending the Xbox Live service, one of the pillars of its video game business, to platforms that are owned by what are ostensibly its direct competitors. The session notes state Microsoft's intention to "connect players between iOS, Android, and Switch in addition to Xbox and any game in the Microsoft Store on Windows PCs".
This would extend Xbox Live's reach from the 400 million Xbox and Windows 10 gaming devices, to a couple of billion devices worldwide.
The news underscores Microsoft's focus on bringing its services to multiple platforms.
As it stands, players using the most updated version of Minecraft on PC can freely join games hosted by other platforms, and have their purchases and history carry over to any supported version, in a similar way to how Fortnite now does it.
This talk - brought to you by the Xbox backwards compatibility team - will go deeper into how Cloud Aware games built with the Project xCloud SDK will help games adapt for mobile through the same graphics and input paradigms as Console Native development.
Sony has started to be more lax with its stance on cross-platform multiplayer, more recently allowing Rocket League to activate the service after an initial rollout with Fortnite.
Microsoft's Xbox BC team has been responsible for the Xbox One's BC feature that makes it possible to play Xbox 360 and original Xbox titles on the Xbox One.
Microsoft plans to expand Xbox Live to other platforms, including Nintendo Switch and mobile.
Saying that's a significant expansion of Xbox Live would be an understatement.