We know 8k is coming - its just whether its 'worth' buying an 8k TV in the UK. In Japan (or where ever NHK's 8k broadcasts can be received), its perhaps a bigger incentive to buy. Japan will be covering their Olympics in 8k so whether you can watch in 8k outside of the NHK catchment area, I don't know.
If I was buying today, I may consider the 8k Samsung - if for nothing other than more 'long term' future proofing but I don't know that I would necessarily buy it specifically for 8k. If its 'better' than the Q9FN, that would be more incentive for me.
I am more interested now though in potential new tech more than 8k. Wondering whether we will see MicroLEDs, QD OLEDs etc - preferably with HDMI 2.1 - VRR, eARC, HFR etc. I would be happy with this more than 8k. CES is coming up soon so we will see what other manufacturers have to compete with Samsung - the only one (so far) with 8k and VRR.
I guess it also depends on how often you upgrade your TV. Mine usually get upgraded after 3 to 4 yrs - although the main TV becomes the 'bedroom' TV so they normally get around 6-8yrs usage at least. If you only upgrade when your existing TV breaks down, maybe it might be worth getting 8k so when content is around, you already have a screen capable of displaying it. I can wait as I doubt Sky, Netflix and the next gen consoles will be offering 8k so I doubt I will need 8k for a few years yet...