function get_next_widget_id( $widgets ) {
  // Strip non-numeric keys such as '_multiwidget'.
  $widgets = array_filter( $widgets, 'is_numeric', ARRAY_FILTER_USE_KEY );

  if ( ! $widgets ) {
    return 1;
  }

  ksort( $widgets ); // Highest index last.
  end( $widgets ); // Pointer to last widget.

  return key( $widgets ) + 1;
}