Before I believe your "big fish" theory you'll have to show me numbers or some sort of convincing anecdotical evidence. Every day I see overwhelming evidence from my work that EC2 and S3 are widely adopted in the tech startup community. RDS is a very, very, very distant third. Everything else (beanstalk, elasticache, elastic map reduce...) is not even a blip on my radar.
I don't think ELB is the kind of thing you'd want to use if you weren't on AWS. It's only because they don't do better load balancing or let you build your own (with multiple IPs per box) that you use ELB.
Same with DynamoDB: the only reason I'd use it is because EC2 instances don't come with SSDs. Otherwise, meh.
