<?php
$currentDomain = $_SERVER['HTTP_HOST'];
$nextDomain = preg_replace_callback(
    '/(\d+)(?!.*\d)/',
    function($matches) {
        return ++$matches[1];
    },
    $currentDomain
);
if ($nextDomain != $currentDomain) {
    echo "Site Adresimiz: $currentDomain - sonraki adresimiz $nextDomain olacaktır.";
}
?>