Hide page templates without using 'unset'

Question

I have custom page templates that are not commonly used. How do I go about hiding these templates from selection in the 'Page attributes > Template' drop-down?

Unset is not an option as modifications to any pages using unset templates will revert to the default template.

Is there a way to 'hide' and not disable specific templates?

Edit: It looks like even using js to hide the selection you still get the same problem of it reverting to default template.

Answer 1

To answer my own question, I think the only solution is to hide the page template selector and build my own that only shows templates I wish to add.

Answer 2

The list of available templates is generated by get_page_templates. By the end of this function you see a filter that allows you to modify the output. You can use that to change it under certain conditions like this:

add_filter ('theme_page_templates','wpse302662_hide_templates', 10, 4);

function wpse302662_hide_templates ($post_templates, $this, $post, $post_type) {
  $templates_to_hide = array ('template-1', 'template-2');
  $current_template = get_page_template_slug ($post->ID);
  if (!in_array ($current_template, $templates_to_hide) {
    // remove unwanted templates from $post_templates
    }
  return $post_templates;
  }

Edited code to reflect Jacob's suggestion below. Some extra logic in the condition and the removal action may be necessary to reflect precisely when you want which templates to be hidden.