Polyphony Digital has announced 18 open positions, including testers and CG artists, explicitly stating that the recruitment is for the development team of Gran Turismo.
It seems the new installment (possibly Gran Turismo 8) is not expected soon due to the long development cycle. This means the game could debut on the next generation of PlayStation.

On the job page, a message from Polyphony Digital founder Kazunori Yamauchi reads:
«Gran Turismo production team recruitment. It’s been 25 years since I started making Gran Turismo. The main reason we could keep creating it was because of the players. I believe this proves that the work I continued truly resonated. We are proud to have realized future ideas through art and technology. Yet I always think it’s still not enough to deliver the best experience to players… I want to create the future with art and technology. To those with an insatiable desire to create, we look forward to your passion, technology, and ideas»
A large headline under the message states: «Now hiring staff for the production of Gran Turismo». The openings include tester roles, CG artist positions, and more.
Considering the lengthy development cycle of these games, it’s unlikely we’ll see the next Gran Turismo anytime soon, and it may only be playable on PlayStation 6.

As a Reminder, Microsoft hints that Cyberpunk 2077 may arrive on Xbox Game Pass.