This seems somewhat orthogonal to the question asked. They have Kinesis which competes with Kafka, SQS with competes with a variety of message queues, redshift, dynamo db, etc and it’s my understanding that Athena was originally a fork of Presto. So, they could definitely move more heavily into the caching space if they see there’s demand.
Elasticache is already that competitor. They are scary to be sure but they have some weaknesses. The main one is branding: Elasticache is a white label Redis not it’s own thing, to the point where their own docs use the two interchangeably.
