Core banking, batch processing, highly sensitive data stores? Probably not great candidates for public cloud consumption.
Web properties and services which don't rely on said functionality? Absolutely great candidates.
And the reality is, whether the IT guys like it or not, developers inside of these orgs are consuming cloud because getting a VM in a traditional sense takes forever (for good reason.)
As a result, we're seeing a shift in the industry where the idea of large corps / financial institutions / government are being pragmatic about the idea of a 'hybrid cloud.'
The reality is, adoption of cloud in the enterprise is growing, not shrinking.