Just like audio, the incremental changes will feel smaller with video as well.
When I mostly watched content in SD, and first got access to 720p content, it felt like a huge improvement. Then 1080p felt like another jump, but not as mind blowing as 720p had. Now I regularly watch 4k content on my 50" TV.
Does it look better than 1080p? Definitely.
Would I miss 4k a lot if I didn't have it? Not really.
4k is a nice to have, but 1080p is pretty good as well. The incremental change from 1080p is quite small because 1080p itself is quite sharp for the size and distance with which we watch our TVs.
Similarly 8k will offer minor improvement. I neither believe that it will be completely unnoticeable nor will it be a path breaking change. Most likely manufacturers will never produce a TV smaller than 65" with 8k resolution. At that size, it will mostly be unnoticeable, but placebo will come into play where people will convince themselves that 8k looks slightly better. The real beneficiaries will be people with 100"+ projectors (and televisions, if and when they become available).
Personally, I'd much rather manufacturers focused on features like FALD, better HDR compatibility and standardization, better audio processing capabilities, etc. But these are things that can be written as a side note, but not features which can compel people to upgrade. Manufacturers are interested in getting people to upgrade so that they can sell more. So 2 years down the line, I totally expect 8k to be the new fad, regardless of whether or not content is available. 5 years down the line, 8k TV is likely to be just as common as 4k is today, i.e., most people who can afford to, buy those televisions.
Either way, it's not the end of the world. Just like 4k televisions have come below ₹30k today, we'll have 8k televisions within reasonably affordable prices. Rest assured we'll still have HD Ready, Full HD, and 4K UHD TVs for those who want those.