Panasonic announced the HZ980 as a replacement for HZ960. In many parts of Europe, it is expected this month (if not out already). I suspect that waiting until Black Friday won't get you any better deals. In general, when I used to live in the UK, I found premium TVs to get better sales in the summer or the boxing-day sales. Might be me, or the models I was looking at.
Sony is keeping the AG9 in its lineup, so it is unlikely that it will disappear. It is also unlikely that it will see significant price cuts. Unlike the AG8, which is replaced.
In my view, if you can get a good deal now, go for it and do not look back. The GZ950 is a great TV. It passed my expectations. The differences between this and the HZ980 boils down to the Filmmaker and Dolby Vision IQ modes. Arguably, neither is worth the price premium. Switching between Professional 1 and 2 modes should suffice and, to be honest, I can hardly see how it could get any better in 95%++ of the situations.
PS: Make sure you get it from a reputable seller. Richard Sounds and other more specialised stores tend to offer significant better warranty and aftersales support than the likes of PC Word/Curry's and can price match non-grey stock. Supporting a local store is also a bonus if you can. ;-)