When does Grounded become available for Xbox Insider?

When does the content become available on PS4?

Hi ignorancik

As the your length of time in the Xbox Insider program and Insider XP level increased additional tiers of the Insider program will become available to you.

https://support.xbox.com/en-US/xbox-one/console/xbox-insider-program

Hi there. Sometimes it is predetermined by the publisher or Xbox if certain games will be available digitally Day 1 in certain countries. However it seems MGSV is not available digitally on Xbox 360 at all. Ground Zeroes is, but not Phantom Pain. There is
a possibility of it becoming available later, but for now, you can only play MGSV on retail discs on Xbox 360

I can't change my Gamertag (GT).

Just because you can't friend request a GT doesn't mean it is available. First of all, all GT are tied to services like Zune or Games for Windows LIVE. If a GT doesn't exist on Xbox, it might be in use on one of those services. Also, spaces and capitalization
are not considered when looking for available GTs. For example, "Major Nelson" is the same as "MajorNelson" is the same as "MaJoR nElSoN". Basically if the service says the GT isn't available, it isn't available.

I heard old GTs are being re-added. When will "This GT" be available?

There is no schedule or estimated dates for when certain GTs will become available again. GTs are not an on-demand service. They will be available when they are available.

http://forums.xbox.com/xbox_forums/xbox_support/f/12/t/19165.aspx#gt

There's no way to know exactly how inactive an account is since they can be used on more than just Xbox. So there's no way to know ahead of time when the tag will be freed up.