Função para retornar um conjunto de datas de dias específicos $days — a partir da data atual — com tamanho $limit.

next_days.php

<?php

function get_week_by_date($date) {
    $date = strtotime($date);

    $week_position = date('w', $date);

    // Seeking sunday
    $sunday = ($week_position == 0) ? $date : strtotime('last sunday', $date);

    $week = [];

    // Adding sunday
    $week[] = date('Y-m-d', $sunday);

    // Adding other days based on sunday
    for ($i = 1; $i <= 6; $i++) {
        $day = date('Y-m-d', strtotime("+{$i} day", $sunday));

        $week_position = date('w', $day);

        $week[$week_position] = $day;
    }

    return $week;
}

function next_days($days, $limit) {
    $i = 0;

    $last_week = date('Y-m-d');

    $result = [];

    while ($i < $w) {
        $week = get_week_by_day($last_week);

        foreach ($days as $day) {
            if ($i < $limit) {
                $result[] = $week[$day];

                $i++;
            } else {
                break;
            }
        }

        $last_week = date('Y-m-d', strtotime('+1 week', $last_week));

        if ($limit >= $i) {
            break;
        }
    }

    return $result;
}