With Windows 10 we saw the introduction of branches controlling how frequently you want to receive feature updates. The Current Branch for Business allows you to defer updates but only two CBB versions are supported at any time so you do have to install the updates at some point. Microsoft announce that the latest CBB build (1607) is available in the VLSC on 26 January, 2017 and thus the grace period for the original CBB build (1507) begins and it will no longer be serviced after May 2017.

Read the announcement here: http://bit.ly/2laW8fu.