Dynamically create sidebars for all pages/posts that match the criteria given. In the example below they must match 'pages', 'published' and be of template 'template-generic-sidebar'.

dynamic-sidebar-creation.php

/* ========================================================================================================================

    Create sidebars for pages

    ======================================================================================================================== */

    $get_pages_args = array(
    'post_type' => 'page',
    'post_status' => 'publish'
    );
    $all_pages = get_pages($get_pages_args);
    $counter = 0;
    $sidebars_required = array();
    foreach($all_pages as $page){
        $page_id = $page->ID;
        $page_template = get_page_template_slug($page_id);
        if (strpos($page_template,'template-generic-sidebar') !== false) {
            $counter++;
            $page_details = array(
                "ID" => $page_id,
                "title" => $page->post_title,
                "slug" => $page->post_name,
            );
            array_push($sidebars_required,$page_details);
        }
    }
    for ($i = 1; $i <= $counter; $i++) {
        $array_counter = $i-1;
        $args = array(
            'name'          => __($sidebars_required[$array_counter]['title'].' sidebar'),
            'id'            => 'sidebar-'.$sidebars_required[$array_counter]['slug'].$sidebars_required[$array_counter]['id'],
            'before_widget' => '<li id="%1$s" class="widget %2$s">',
            'after_widget'  => '</li>',
            'before_title'  => '<h2 class="widgettitle">',
            'after_title'   => '</h2>'
        );
        register_sidebar($args);
    }