As cited in the Xbox forums, Xbox Live accounts are now supported with region migration. However, it comes with a few caveats that aren’t so user-friendly:
All of your current subscriptions, except for Xbox Live Gold if you had any, will be cancelled.You may lose the ability to re-download some, if not all, of the content in your download history.
Any content that you will subsequently download after the account is migrated will be subject to any applicable geofencing rules of your new location.
“Geofencing” might be the biggest inconvenience here, as it essentially requires you to repurchase contents that’s already been paid for across a regional border. At very least, though, you get to keep your achievements.
Microsoft Support also notes that the migration process can take up to six weeks, SO use your Xbox Live Gold Membership or don’t get it until you’ve done the switch.
