It’s an attractive story: Public cloud services that can allocate applications and services to users through a cloud broker. These brokerage systems sit between the consumers of cloud services and the services themselves.
Brokers can gather data about the cloud service -- including cost, efficiency, and functionality -- to help you make better decisions about which cloud service best meets the needs of the cloud service consumer. You can place many public and private cloud services behind the broker, then have it broker to the best service for your application.
Though attractive, the sales pitch is a bit different from the reality. Most cloud-based applications have to be localized for the cloud platform they use. If you've allocated EC2 and S3 instances from AWS and you use the cloud-native features of that platform, then you're pretty much locked onto that platform. You're not able to easily use other cloud services, such as those from Microsoft or Google, all of which means a cloud service broker won't help outside the use of generic cloud services.
In fact, using cloud service brokers may cost you more in the long run because you'll need the in-house expertise for each service that the broker might allocate. Of course, you may want to have those skills anyhow; although using one provider is easier, most IT organizations want to keep their options open -- for good reasons.
What might make cloud service brokerage more broadly useful is the containerization of applications. Containers should be able to work with most cloud services, so they can truly be allocated to whatever cloud service makes the most sense at the moment, yet retain their custom capabilities. This too is another great vision, though it's easier to say than do.
Moreover, I’m not certain that enterprises are actually interested in moving applications -- containerized or not -- from cloud to cloud, even if they can. Such resource arbitrage adds complexity and variability that are perhaps better handled by monitoring your actual usage and scaling your chosen cloud service SLAs accordingly.
Cloud service brokers are a great concept, but they may not be so great in the real world.