To Tony's comment about the actual necessity of 4K as a delivery format, "I sometimes feel like HD on a relatively large monitor is almost too much fidelity for most average size rooms…", it's a good time to revisit Stu's blog post about 4K TVs in the home from January of 2013:
http://prolost.com/blog/2013/1/22/4k-in-the-home.html
The chart basically shows that at a close 6' viewing distance, one would need something like a 100" TV to see the full benefit of 4K over regular 1080 content.  Which is a massive TV.  The article nicely and succinctly explains why good black levels and contrast ratio are more important than actual resolution when it comes to perceived display resolution.  He notes that 4K makes sense "if you’ve got a projector, a huge screen, a close seating distance, and perfect eyesight."  It's a good blog post to have in your back pocket when people start talking about this stuff or a friend is buying a TV.
Will 4K become a "thing" as a delivery format anyway? Â Maybe. Â Probably? Â It'll probably compressed to hell while render times will quadruple and storage requirements will go up.
People's points about the benefits of it as an acquisition format with 1080 delivery are solid, though -- camera tests I've watched of the 4K Blackmagic camera downresed to 1080 versus other cameras capturing native 1080 are impressive. Â There is detail and sharpness for days.
Regardless, Stu's post and the included chart is worth a look. Â Check it out.
 - Nathan
