Actually, I'm pretty sure 35mm is equivalent to slightly higher than 4k resolution...and if you start talking IMAX footage, it's way higher than that. That said, the true benefit of 4K isn't the extra resolution...it's the color depth and HDR. The resolution bump can sometimes be noticeable, but as mentioned above, it's definitely at the point of diminishing returns. The color depth and contrast improvement from HDR though...that's huge on a well adjusted display. I was a doubter up until I finally made the upgrade a few months ago. Yeah...blu is awesome...but 4k is definitely on another level. As with every format though...a lot depends on how well it was mastered and transferred. A great Blu will still look better than a crappy 4k. But all things equal, 4k blows it away, and I never expected to say that.

And that's only half the story. Dolby Atmos / DTS:X are the other half, and are another huge leap forward, but on the audio side. Yes, you can get those on standard Blu, but its much more prevalent on 4k.

Good Blu is a perfect picture. Good 4K is a window you could reach into.

Mostly agree. On my 65", you can definitely see the resolution difference, but it isn't huge. If you A-B back and forth, the difference is apparent (again, with a good source), but I'm not sure if I could pick out one or the other on resolution alone. The contrast and color depth from HDR though...that CAN be very dramatic on any size display. That was my biggest surprise making the upgrade.

Yes, there are a few standard Blu-rays with Atmos, but not many. The TMNT reboots, Bumblebee, and most of the DC Universe movies are a few examples. I think the newest Jurassic World movie has a DTS:X track. Definitely not many compared to 4k discs though.

After being a huge DVD and Blu-ray home theater enthusiast, I resisted 4k for a very long time thinking there was no way the upgrade would be worth it. I was wrong. On average it definitely isn't as huge as the leap from VHS to DVD or the jump from DVD to Blu, but it is definitely a very fun upgrade.

I do not have experience with OLED, but I will say that the new Samsung QLEDs (Q70 and up at least) are surprisingly good at black levels. I upgraded from an older LED which was higher end at the time, and the difference was night and day. The multizone localized dimming really makes a big difference.

As for the 8k...why? What will you watch on it? I do not think there is any source material available, or if there is, there sure isn't much.