diff --git a/src/black/lines.py b/src/black/lines.py
index 9963bc9..d961249 100644
--- a/src/black/lines.py
+++ b/src/black/lines.py
@@ -290,8 +290,7 @@ def has_magic_trailing_comma(
 
         if closing.type == token.RSQB:
             if (
-                Preview.one_element_subscript in self.mode
-                and closing.parent
+                closing.parent
                 and closing.parent.type == syms.trailer
                 and closing.opening_bracket
                 and is_one_sequence_between(
diff --git a/src/black/mode.py b/src/black/mode.py
index 190ad25..dbc45d2 100644
--- a/src/black/mode.py
+++ b/src/black/mode.py
@@ -150,7 +150,6 @@ class Preview(Enum):
     """Individual preview style features."""
 
     long_docstring_quotes_on_newline = auto()
-    one_element_subscript = auto()
     remove_block_trailing_newline = auto()
     remove_redundant_parens = auto()
     string_processing = auto()