People asked: "what do you mean by "pure" IaaS?" It is a legitimate question, as the bare iron needs an operating system, some utilities, in order to be usable. In reality "pure IaaS" is the absolute minimum PaaS required to set up a server or a cloud infrastructure.
How do we define the "minimum" PaaS? Some IaaS providers take themselves the decision -take it or leave it - on behalf of the customers. Very few IaaS providers, like CloudSigma, are offering customers the freedom to choose what they need, what it works for them, what they like.
Worth mentioning, another strategy for customers is to use an abstraction layer. Good ones include jclouds and libcloud. Still take the point about focus/quality.
Yes this is definitely possible and a multi-vendor approach in the cloud is achievable at quite a low bar in terms of customer size. You only need to look at outages at Reddit and many others to see the benefit of that approach.
Yes, all cloud brokerage attempts have so far stuck to the resources and avoided trying to do any unified billing. Its really tough to accomplish.
Can you think of other areas where competing services have common open billing? Great for sure but difficult commercially. Especially when you start bringing in credit risk and other non-technical factors.
I agree that this is difficult. I wasn't really thinking about competing providers though; more like complementary. Like getting IaaS from one company, CDN from another, DNS from another, etc. One could imagine a federation of pure-play service providers that might be able to compete against the more integrated cloud juggernauts while each company focused on one thing.
How do we define the "minimum" PaaS? Some IaaS providers take themselves the decision -take it or leave it - on behalf of the customers. Very few IaaS providers, like CloudSigma, are offering customers the freedom to choose what they need, what it works for them, what they like.