Remove subpage_types logic from is_navigable and get_navigation_menu_items. It's now clear that we will never mandate the use of subpage_types, so we can't use its presence or absence as an indicator of whether or not a page is appropriate to be included in navigation menus.

wagtail/wagtailcore/models.py

@@ -414,10 +414,10 @@ class Page(MP_Node, ClusterableModel, Indexed):
     def is_navigable(self):
         """
         Return true if it's meaningful to browse subpages of this page -
-        i.e. it currently has subpages, or its page type indicates that sub-pages are supported,
+        i.e. it currently has subpages,
         or it's at the top level (this rule necessary for empty out-of-the-box sites to have working navigation)
         """
-        return (not self.is_leaf()) or (self.content_type_id not in get_leaf_page_content_type_ids()) or self.depth == 2
+        return (not self.is_leaf()) or self.depth == 2
 
     def get_other_siblings(self):
         # get sibling pages excluding self
@@ -654,13 +654,8 @@ class Page(MP_Node, ClusterableModel, Indexed):
 
 def get_navigation_menu_items():
     # Get all pages that appear in the navigation menu: ones which have children,
-    # or are a non-leaf type (indicating that they *could* have children),
     # or are at the top-level (this rule required so that an empty site out-of-the-box has a working menu)
-    navigable_content_type_ids = get_navigable_page_content_type_ids()
-    if navigable_content_type_ids:
-        pages = Page.objects.filter(Q(content_type__in=navigable_content_type_ids)|Q(depth=2)|Q(numchild__gt=0)).order_by('path')
-    else:
-        pages = Page.objects.filter(Q(depth=2)|Q(numchild__gt=0)).order_by('path')
+    pages = Page.objects.filter(Q(depth=2)|Q(numchild__gt=0)).order_by('path')
 
     # Turn this into a tree structure:
     #     tree_node = (page, children)