In reply to kimstuart12345.

There is no plan to remove Themes from the directory. Existing Themes will remain just as they are. When/if the developer attempts to update the Theme, the updated Theme will not pass the review/approval process unless/until it conforms to the Customizer requirement for any Theme options.

Note that, separate from the work of the Theme Review Team, Themes (and Plugins) that have not been updated within two years are automatically hidden from directory search results. So, yes: if a Theme goes un-updated for too long, regardless of the reason, it will eventually not be searchable. (Though such Themes can still be found directly.)

That people think that Themes will "get the boot" is not an idea propagated by the Theme Review Team. More likely, the misconception is borne out of incorrect/incomplete reporting, or false assumptions.