Why not? You can assign a domain to S3 buckets. It can be just as pretty as it is today. The only difference is if he serves them directly from S3, the domain will be different from the creation API.
But considering the additional features he's planning on adding, he will probably need to proxy S3 anyway, so not sure if it's worth it in this case.
But for something of the scope of the current API, S3 is the perfect solution.