You can read it here: https://mailchimp.com/resources/introducing-your-new-audience-dashboard/
Reasoning for posting: we just received notice of this change and may receive a large bill unless we fix it today. So, we're manually archiving unsubscribed contacts via MailChimp in the interim - perhaps this affects others.
The largest change I see is that Mailchimp will now offer CRM like features and also bill customers based on their "Total Audience" vs the "# of people who are subscribed" - which means if the MailChimp extension unsubscribes someone they will still be billable.
A list with 15,000 subscribers is billed approx $150/m as I currently see it.
Is anyone aware of plans to update this extension with consideration of the new change (for instance, to "archive" unsubscribed contacts so they are not billed?)
Extension Page: https://github.com/veda-consulting/uk.co.vedaconsulting.mailchimp/ * Thanks Veda for contributing this wonderful extension to our community.
UPDATE 1: Mailchimp support says we can stay on our existing plan for the time being, and we will not be charged according to the rules of the new plans (announced tomorrow).