For some AWS services, such as Elastic Beanstalk, there appears to be no way to avoid consuming a public IPv4 address on the EC2 instances, except by introducing a NAT gateway.

(And "NAT gateways are an extremely cost prohibitive device in AWS, costing at least as much per day as medium sized EC2 instances!")

https://github.com/aws/elastic-beanstalk-roadmap/issues/208