Numerous companies depend on s3. Along the way open-source solutions have been built, as well as competitive solution that are API-compatible.
We're seeing the same in serverless. Frameworks that are moving toward multi-cloud, competitive solutions, etc. While not totally portable, you can take much of your code with you. You'd do the same if you had a standard Rails app running on an easy-deploy solution like Heroku and had to move to Digital Ocean. In other words, the potential for vendor lock-in is a problem that we've been created patterns to solve for many years.
>> That'll be <way too many $$> and you got nowhere to run
That makes for a great conspiracy theory but AWS has never done anything remotely like that. Through the history of the service they continue to bring down the price on their various offerings. Not sure what makes Lambda the piece they'd abandon all that for (insert evil laugh) world domination.