Oh the "service bus" <strike>xml</strike> json is coming back... its called lambda architecture.
And again nothing new except someone else takes care of some server software for you with the promise of reduced price and maintenance but the reality eventually becomes tight proprietary coupling and eventual price gauging.
Amazon's own Lambda is that, yes. But the Lambda architecture it inspired is the opposite: a de-facto standard (based on the way Amazon's works, but probably eventually an open standard) for servers any org can use to stand up their own public or private FaaS cloud, which developers can deploy Lambda functions onto rather than having to build an entire container/VM just to slot it into OpenStack.
I doubt it will ever be a standard. Amazon loves vendor lock in. Plus most of the cloud services love to do their own thing for each service type. The main exception seems to be Kubernetes. Google has it in GCE, and Amazon has said they are working on their own Kubernetes service. If that happens, I bet Azure will follow if they aren't already working on it.
I (and others) are not so much imagining a standard between cloud vendors, as we're imagining a standard "FaaS server function API" (sort of like how the web has a standard DOM API) supported by several FOSS FaaS server implementations (sort of like how the web has several FOSS Javascript engines.)
Given such a standard API and compatible servers, you'd then deploy a FaaS server cluster to your public/private cloud of choice, the same way you deploy e.g. a Kubernetes cluster, or a Riak cluster.
There would likely by small public clouds attempting to be "FaaS native" by exposing only such servers in a multitenant configuration (like small public clouds like Hyper are currently doing with CaaS.) Their implementations wouldn't always be exactly compatible, and might have some lock-in.
However, once FaaS "caught on" with the enterprise, a FaaS server would likely make its way into the OpenStack architecture.
At that point, you'd see medium-sized public cloud providers like OVH and DigitalOcean set up their own multitenant FaaS clusters as well, probably with custom code, but built to be compatible with the OpenStack FaaS tooling, to allow enterprises the freedom to move FaaS functions freely between public and private clouds.
And, eventually, the other major cloud providers would feel the need to support the API.
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This path has already been followed: it's what happened to Amazon S3—first cloned (but not compatibly) in FOSS by tools like Riak CS; then standardized by OpenStack Swift; then cloned compatibly in FOSS by tools like Minio; then picked up by medium-scale clouds like Rackspace; and then, eventually, picked up by Azure and GCP as secondary APIs to address their equivalent offerings (that originally had quite different APIs.)
And again nothing new except someone else takes care of some server software for you with the promise of reduced price and maintenance but the reality eventually becomes tight proprietary coupling and eventual price gauging.