VMware releases new versions and products with advanced features and enhancements for their customers. And there will be always time to move to next generation products due to end of support and for more advanced feature usage. VMware vSphere 5.5 is really End of Support and no more updates and possible limited support from VMware.
The End of General Support for vSphere 5.5 was September 19, 2018. To maintain your full level of support and subscription services, VMware recommends upgrading to vSphere 6.5, or to a newer version. Do not get panic technical Guidance for vSphere 5.5 will be still available until September 19, 2019 primarily through the self-help portal. During the Technical Guidance phase, VMware does not offer new hardware support, server/client/guest OS updates, new security patches or bug fixes unless otherwise noted. For more information, visit VMware Lifecycle Support Phases
Which version should upgrade?
All version 6.x have an active general support and the best choices are to upgrade to version 6.5 (and not to 6.0). If you would like assistance in moving to a newer version of vSphere, VMware’s vSphere Upgrade Service is available. This service delivers a comprehensive guide to upgrading your virtual infrastructure. It includes recommendations for planning and testing the upgrade, the actual upgrade itself, validation guidance and rollback procedures. For more information on the benefits of upgrading and how to upgrade, visit the VMware vSphere Upgrade Center.
In the event you are unable to upgrade before the End of General Support (EOGS) and are active on Support and Subscription, you have the option to purchase extended support in one year increments for up to two years beyond the EOGS date. Visit VMware Extended Support for more information.
In addition this i would like to share an update on other version ,vSphere version 6.5 U1, VMware has extended the general support for vSphere 6.5 to a full five years from the date of release, which means the general support for vSphere 6.5 will end November 15, 2021. Also note that, actually the date it’s the same both for 6.5 and 6.7.
Additional Reference and Uweful Links
vSphere 6.7 – Upgrading from vSphere 5.5