Amazon has announced that they are dropping their unlimited storage plan. A disappointing move, but not all that surprising. You can learn more from their FAQ here: https://www.amazon.com/b?node=16591160011
Highlights from the FAQ:
Amazon will no longer offer an unlimited storage plan. Instead, we’ll offer storage plans of 100 GB for $11.99 and 1 TB for $59.99, up to 30 TB for an additional $59.99 per TB.
You have a 180-day grace period to either delete content to bring your total content within the free quota, or to sign up for a paid storage plan. After 180 days in an over-quota status, content will be deleted (starting with the most recent uploads first) until your account is no longer over quota
Prime members will continue to receive unlimited photo storage as a benefit of their Prime membership, and their photo content is not subject to the over-quota policy.