Ask HN: Is there still room between AWS, Google Cloud and Azure?

That depends entirely on what you define as "room". Rackspace, Softlayer, and many others are competing in that space and are doing quite well. If you define "room" as "beating AWS, Google, and Microsoft" then I don't think there is "room" like that.

We are still in the very early stages of utility computing. There is ample opportunity to build successful products in that space.

I'll just say "go read The Discipline of Market Leaders". I hate to sound glib, but I think you'll find their approach interesting, and I don't feel like trying to summarize the whole book here. It's not long though, and it's definitely worth a read. IMO, anyway.