I was talking with a cloud evangelist the other day and he made the statement that "we're using cloud, we don't need an Enterprise Architecture".
After a comment like that I had to re-booted my mind before I could speak.
Now you need the enterprise architecture more than ever. Just because you've "outsourced" the technical architecture via the cloud of some of the underlying enterprise components, it doesn't mean that this set of services can stand alone. For most organizations it needs to be integrated into the wider enterprise in order to deliver comparable value.
I view that architecture consists of a number of large grained architecture components:
When you move into a cloud approach a few elements of that particular service will be outside your control. For example, if you use a SaaS provider for CRM, the application architecture, the infrastructure architecture, the information architecture and the service management architecture for that particular service will be outside your control, but you still need to understand if it is functioning, and move information in and out of the service, integrating it with the rest of the enterprise. So some of the content will get smaller (in the EA) for that service and service management will get larger. This is one reason Solution Architecture is separate from but complimentary to Enterprise Architecture.
The organizations EA still needs to conform to a process and be a foundation for governance, otherwise you can get yourself into a chaotic situation whose value delivery is unpredictable.
So it is not a choice between cloud and and EA but more of a need to have an EA to ensure the benefits of cloud, s since the EA is focused on aligning the benifits of technology with the business.