When this will happen
Microsoft will begin rollout in early December (previously November) and expect to be complete by end of January (previously mid-November).
How this will affect your organization
For organizations with 10,000 or fewer users, global admins will be able to easily create a public team that includes every user in the organization. Microsoft Teams will use Active Directory to keep membership current.
The limit of five org-wide teams per tenant is unchanged.
What you need to do to prepare
After this rolls out to your tenant, if you don’t see the org-wide option when creating a team and you’re a global admin, you might have reached the five org-wide team limit or your organization might have more than the new size limit of 10,000 members.