In the present cycle (Avasarpini), Mahavira is the 24th and last Tirthankar. According to traditional Jain texts, no new Tirthankar will be born in this cycle after Mahavira. The next Tirthankar will appear in the following cycle (Utsarpini), not in our current time. You can read more about this idea here .
Names of the next Tirthankaras in the future cycle are not fixed across all scriptures and traditions. Digambar sources commonly mention Padmanabh as the 25th Tirthankar of the next cycle, while Śvetambar texts sometimes refer to the next as Mahapadma (the exact name varies). In short: there are no universally agreed-upon “upcoming” names for this future cycle. You can read more here and more about future-cycle lists here .