Many Elastic Beanstalk environments to be retired on March 1, 2020, with additionally Windows Server 2008 R2 to be retired earlier on October 16, 2019
It's unclear what these retirements really mean, with the statement "Elastic Beanstalk may need to automatically remove the Elastic Beanstalk components and transfer ongoing management and support responsibility of the running application and associated AWS resources to the customer."
https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/platforms-support-policy.html