In our present time-cycle (Avasarpini) there will be no new Tirthankar after Bhagwan Mahavir.

So, in simple words:

• Now: We are in the 5th era (Pancham Kaal) of Avasarpini in Bharat Kshetra.
• Last Tirthankar of this half-cycle: Bhagwan Mahavir (24th).
• Next Tirthankar in our Kaal: None. No more Tirthankars will come in this Avasarpini.

In the next half-cycle (Utsarpini), a new set of 24 Tirthankars will arise. Traditional Jain texts say only this much clearly for us:

• Each Utsarpini and Avasarpini has 24 Tirthankars.
• They appear when conditions become suitable for dharma.
• Their detailed names and lives of the next 24 are generally not the focus of present-day practice; our focus is on the teachings of the current 24, especially Mahavir Bhagwan.

You can read a very simple explanation about future Tirthankars here