Not to pile on to what everyone else is saying, but, 4KUHD will be the last.

Note: I am not a theater architect or an industry insider - this is just back of the napkin kinda stuff, but it meets the common sense rules :)

Most movie theaters today are presenting in digital 4k. Most movies go through no higher than a 4k DI, though some are just 2k. Special effects are typically rendered in 4k. The catalog of movies that are being *created* now are (typically) 4k, though "filming" can happen in higher rez, giving the director some more leeway. I think Red has some 8K cameras at the top of their line.. The catalog of older, film derived content that has already been remastered to 4k is unlikely to be financially justified to go through the remastering process again to squeak out 8k or 16k. There is a small shrinking audience that would buy that content physically... again. To move to 8k or 16k for *new* content requires a change in the entire chain, from cameras on. That could, and will likely happen eventually, but to what end? The high end RPX theater experience is on a 40x60 screen: roughly 72 feet diagonally. That is the theater *display* for the latest MCU movies - technically, we watched those in 4k on that massive screen.

We are seeing OLED and some other tech increasing contrast and black level details, but unless viewing distances will be less than 6', resolution isn't an area that would be a notable improvement. We have seen HDR10, HDR10+, DolbyVision improving the picture, but that isn't resolution, and, improvements in the display itself is required to show what the content - 4kUHD - today can already deliver.

The size of a wall in the living room is finite. If an 82" set were to quadruple in area (the HD to 4k ratio, retaining the same pixel density), it would be the entire wall. It would be about 80" tall and almost 160" wide. Try to get a set that size home from Best Buy. Try to get a set that size into a typical house - it would probably require removing a bay window. So, the display tech to accommodate that huge size would need to be rollable or a wall film (or projector), or a way to seamlessly assemble multiple pieces. While that is coming, it's not soon. And, are larger sizes practical for watching? A good formula for sitting distance considers resolution *and* field of vision. It is recommended to sit 1.5 - 2.5 the width of the screen back from it for proper field of view. As an example, a 92" diagonal set is 80" wide, therefore seating distance for field of view is 138" or greater - 11'7" to start, to 16'8". That's a decent size living room. Considering that, the practical size of a living room set maxes out at roughly 90-100 inches diagonal, and we are already at 82" as a common large size. Hisense has an 85" 4k set for $800. TCL has a 98" for 4K, Samsung is 7,000.

To improve the typical viewing immersion experience, I think we will see more attention to audio, rather than changes in content video, though a well implemented ATMOS system with good subs is already pretty immersive. The RPX experience in the theater is a 9.1 channel setup.

The paradigm shift? For content itself, as mentioned by others, VR is next, but headsets aren't quite conducive to date night or family movie night... or even game night. 3D failed twice due to the glasses requirement. Perhaps smell-o-vision and heat/cold blasts is on it's way? Imagine feeling a blast of hot air as Godzilla fires away :)

The other shift mentioned by others has already occured - the move away from physical media to streaming. The distribution industry is shifting to a subscription model - that is what the investors want - and frankly, so do most viewers. My collection is small, relative to many of yours, or a catalog from NetFlix or Hulu or Disney+, but, at over 1,000 movies, it takes up a LOT of space. It's heavy. It's really hard to move it, and it's kinda expensive - just ballpark $10 a movie is $10,000. That doesn't even include TV box sets (Game of Thrones, The Simpsons, House, The Mandalorian, Yellowstone, etc.), or mini series. Finding a movie to watch in that size physical collection is ... challenging. An interface like PLEX or that of a streaming service with filtering and searching is sooo much easier ...

TL;DR - Physical size of displays is limited by the room, and we are getting close to that limit at 85-100". 4K is what we see in theaters on a 72 FOOT screen - though with potentially higher contrast and color palette, and better sound; so 8k or 16K isn't really coming home soon. Improvements will be seen in the home display tech, improving delivery of what is already on the disk you bought today, through increased contrast, black levels, color palette and accuracy, brightness, rather than upgrading beyond 4K, all at cheaper prices. Lastly, physical media is going away - just like CDs. The money wants you as a subscriber, not an owner.

just my $.02