Roughly, yes. I'm just happy to see that there are 3 now, instead of only Amazon.

It depends how you define "the space", of course. Dropbox, GitHub Pages, Heroku, and many more can be used to host static content. But I think this is an accurate list if you want something that is a) dirt cheap at any scale, b) fast and reliable, c) meant for this purpose, d) configurable enough to host a professional website without embarrassing quirks, e) not overly tied to a particular platform configuration.

I suppose Microsoft Azure (CDN) could be considered a contender in the same space.

Possibly dropbox (html & assets in a public folder) might be considered.