I imagine 8k, or maybe 16k will be the end of increasing resolution. At 16k, even with a 70 inch screen, you'll have as high pixel density as I have on my iphone. And while my iphone isn't the most impressive piece of tech screenwise, it is usually tops 50 cm away from me. Even just by doubling the distance to a meter would mean you got 4 times as many pixels covering the same field of view, and who on earth are only a meter away from their TV?
Maybe someone with obscene amounts of money will do 32k for the luls, but I really don't think you'll be able to tell at that point.
I do find it hard to believe that people will need 32k, and I strongly advocate for 8k.
Though that could just be ignorance.