After talking with @aspilicious, it seems this is what is necessary to support Display Suite in Drupal 8. Whenever Display Suite is used to render a "real field" differently, then `#field_name` should still be set. Whenever it is used to render a "pseudo field", then `#field_name` should not be set. Then no corresponding `data-edit-id` attribute…

edit_ds.patch

 core/modules/edit/edit.module |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/core/modules/edit/edit.module b/core/modules/edit/edit.module
index a7fbb5d..a174e4e 100644
--- a/core/modules/edit/edit.module
+++ b/core/modules/edit/edit.module
@@ -162,6 +162,11 @@ function edit_field_formatter_info_alter(&$info) {
  * Implements hook_preprocess_HOOK() for field.tpl.php.
  */
 function edit_preprocess_field(&$variables) {
+  // Drupal contrib may render "pseudo fields" that don't map to "real fields".
+  if (!isset($element['#field_name'])) {
+    return;
+  }
+
   $element = $variables['element'];
   $entity = $element['#object'];
   $variables['attributes']['data-edit-id'] = $entity->entityType() . '/' . $entity->id() . '/' . $element['#field_name'] . '/' . $element['#language'] . '/' . $element['#view_mode'];