Before you think that Microsoft no longer support an on-premise version of Exchange, be aware that this is a new option in the Existing Exchange Deployment Assistant.
Quoting from the entry on the Microsoft Exchange Blog:
To help you sort through the available options and plan your migration to the cloud, we’re happy to announce the “Cloud Only” option in the latest release of the Exchange Server Deployment Assistant. Like the other scenarios in the Deployment Assistant, the “Cloud Only” option allows you to step through a wizard that asks you questions about your current infrastructure and your migration goals. The Deployment Assistant will provide a migration solution that is based on your answers.
Great for customers and consultants evaluating cloud options.