Ec2 classic networking is going away this month.

But that's ancient technology at this point.

To the best of my knowledge, no. At least none of the AWS services I've used. They've deprecated support for some CAs and stuff, but that seems reasonable.

There have been rare changes, like mandatory API version upgrades or some features being turned off. I do not recall anything being removed without a (better) replacement available beforehand, let alone entire simply services being turned off. See simpleDB as the canonical example of long term deprecation but continued availability.

Disclosure: long time Principal at AWS. The above is my own observation and opinion

Not that I'm aware of. They'd be fully justified in shutting down simpleDB since it hasn't had a feature update in over a decade, but they still keep it running. New accounts can't sign up for it and it only exists in the oldest regions.

They were going to retire old s3 path styles, but they changed their mind after customer feedback.

There was an ML service before sagemaker that you can't start using anymore but I believe it still works for existing customers

Yes: Amazon Sumerian.