As organizations begin to adopt public cloud, one element of consideration is what to do with existing applications. These applications were not built with cloud in mind, though most are virtualized today. These organizations must now determine a modernization strategy for these applications and incorporate how public cloud might fit into the picture. This paper examines the use of public cloud for data center extension and replacement, particularly in light of existing traditional enterprise applications. It also looks at the role of VMware's vCloud Air public cloud service in meeting the needs of these applications.