As mentioned in the video, RX 7600 is already a full Navi 33, so a RX 7600 XT can't be based on Navi 33. A higher clocked RX 7600 sold as RX 7600 XT would be lame.
Also, I don't think they can make a RX 7600 XT based on Navi 32 either.
That means AMD would need a Navi "32.5" for such a card.
I think most likely AMD will re-use Navi 22 (RX 6700 / RX 6700 XT / RX 6750 XT) for a "new" RX 7600 XT. Those fit the performance and VRAM sizes (10GB / 12GB).