In Jain cosmology, Tirthankars and other Kevalins in Bharat & Airavat Kshetra appear only in the 3rd and 4th era (ara) of each half‑cycle (whether Avasarpini or Utsarpini).

So for your question:

> Will the next Kevalin (Tirthankar) appear in the 3rd era of Utsarpini?

Yes. In the next Utsarpini of our Bharat Kshetra:

• Tirthankars (and thus Kevalins who establish sangh) will again appear.
• They will appear in the 3rd and 4th ara of that Utsarpini.
• The first Tirthankar of the next Utsarpini is traditionally called

- Padmanabh in Digambar tradition - Mahapadma in Shwetambar tradition ( jainknowledge.com)

So, yes, Kevalins (including Tirthankars) will appear in the 3rd era of Utsarpini, and will continue in the 4th era as well.

You can read a simple explanation of Kalchakra (Utsarpini–Avasarpini and Tirthankars) here: “Understanding Jain Kalchakra (Time Cycle)”