I actually can see pixelation on 1080p on 60" plus sets. 4K is welcome once the price is right.
Being able to see pixilation is dependent on viewing distance, not screen size.
With a 60" 2K screen, you might begin to see pixilation closer than 8 feet.
With a 60" 4K screen, you might begin to see pixilation closer than 4 feet.
Since my TV set is about 10 feet from my chair, I would not be able to see a difference in sharpness or clarity between the two, so it would be a total waste for me to invest in a 60" 4K TV.
If you were to get a Mac Pro with a 30" 4K monitor, you would need to view it from less than 18 inches to get full benefit. Next time you're at an Apple store, try viewing a 30" monitor from 18 inches or less for an extended period. Sorry, but that's just too close and too big for my comfort.