Can "Display Name" be a drop down?

Hello,

Create a dropdown with meta_key: display_name, and add following codes to functions.php

add_filter( 'user_meta_field_config', 'displayNameDropdown', 10, 4 );
function displayNameDropdown( $field, $fieldID, $formName, $userID ){
    if ( $fieldID <> 'XYZ' ) return $field;

    $profileuser = new WP_User( $userID );

    $public_display = array();
    $public_display['display_nickname']  = $profileuser->nickname;
    $public_display['display_username']  = $profileuser->user_login;

    if ( !empty($profileuser->first_name) )
        $public_display['display_firstname'] = $profileuser->first_name;

    if ( !empty($profileuser->last_name) )
        $public_display['display_lastname'] = $profileuser->last_name;

    if ( !empty($profileuser->first_name) && !empty($profileuser->last_name) ) {
        $public_display['display_firstlast'] = $profileuser->first_name . ' ' . $profileuser->last_name;
        $public_display['display_lastfirst'] = $profileuser->last_name . ' ' . $profileuser->first_name;
    }

    if ( !in_array( $profileuser->display_name, $public_display ) ) // Only add this if it isn't duplicated elsewhere
        $public_display = array( 'display_displayname' => $profileuser->display_name ) + $public_display;

    $public_display = array_map( 'trim', $public_display );
    $public_display = array_unique( $public_display );
    $public_display = implode( ',', $public_display );

    $field['options'] = $public_display;

    return $field;
}

Don’t forget to change XYZ with field id.

Thanks.