When will Roland announce its new arranger keyboard?

Who knows? but the Go Keys 3 and 5 are pretty interesting.

Although, I wouldn't expect an updated version of the G-70 or the BK-9 as a competition for the Yamaha Genos or Korg PA5X, but it would be nice.

Good question, but I have a feeling that Roland has left the arranger keyboard market.
I highly doubt that there will be anything new, at least not in the MOTL and TOTL segment.
It has been too long since the last ones .......

Only the future will tell how long Yamaha, Korg and Ketron will continue to develop their model lines. 🤔
In the meantime,
we can still have a great time and enjoy the brands and models we have and that are still available. 😉👍