Update: Xbox One cloud updates will NOT forcefully restart the console. A bit more clarification was given by one of our readers (thanks Drewidian!). He explains the process perfectly:
1) new patch is released to servers which will download and queue it for install and reboot. New requests will be sent to servers who are already patched or are slated to get the patch later.
2) no new matches/connections will be allowed to connect to a server with a pending update.
3) once all of the matches/sessions have ended on this server, it will install the patches and reboot.
4) once the server comes back up and is fully patched, it will allow new connections.
This is how its been done for YEARS people! You will not get disconnected from an active server.
You can read the original story below, which was published earlier today:
Xbox LIVE's lead program manager, John Bruno has revealed that the Xbox One will frequently update its cloud service, which can result in the console restarting. This restart will apply whatever updates are downloaded, but what's worrying is that these updates can forcefully restart the console, no matter what you are doing.
Bruno claims that "once in a while, rather frequently actually, the host OS will require an update, meaning the physical machine is going to get rebooted whether your code is running or not," he explained. "That’s a problematic thing for a game, and oftentimes it's in the middle of a multiplayer session. We’ve worked very hard to overcome that, but that’s not to say it’s going to be a reality in every case."
Games which are heavily based on the new Xbox LIVE Cloud service could become unplayable during these update times, which again is another rather large issue. Bruno says that game developers can decide how heavily integrated their game is with the Xbox LIVE Cloud service.
These reboots will definitely be an issue for gamer, but as Bruno mentioned above, Microsoft has tried its best to stop this from happening mid game. It's possible that scheduling an update period, like large MMO's, could somewhat mend this problem. The updates could occur during the early hours of Monday morning, where gamers wouldn't generally be playing.