I work in the AWS Mobile org. The predecessor to our premier service, Amplify, was called Mobile Hub (https://aws.amazon.com/blogs/aws/aws-mobile-hub-build-test-a...). While I haven't personally worked on either service, I've heard and seen enough to know that they've taken customer obsession over keeping the lights on for any existing workloads farther than most reasonable businesses would. There is no sentiment of "force them to move to Amplify" in any conversations or design discussions, but rather "accommodate their existing workloads" as long as they exist.

Update: it looks like we're executing a migration plan this year by building seemingly-full parity between Mobile Hub and Amplify (https://docs.aws.amazon.com/aws-mobile/latest/developerguide...) such that "if you don't migrate your project to Amplify, your app will continue to function, and all your related cloud resources will continue to be available". This seems like a great solution for existing Mobile Hub customers.