He is correct - with what we currently call 4K. Current 4K is a crippled version of what is to come. For example, you cannot do 4K at 60Hz - HDMI 1.x simply cannot push any more data than that. HDMI 2.0 will fix this problem, but then you will need all new equipment and cables for it.
The first crop of 4K Ultra HD TVs from Sony, Samsung, LG and Toshiba have HDMI 1.4 ports that can feed full resolution 2160p (4096 x 2160) Ultra HD signals, but there’s a catch — they can only do so at 24 or 30 frames per second. That’s works fine for movies, but is of no use for gaming and TV broadcasts, which require 50 or 60 fps.
There is a caveat to note, too, especially if you’re looking to buy one of the first 4K Ultra HD sets available. Those sets won’t be compatible with HDMI 2.0 because it hasn’t come out yet. What that means is the TVs would have to drop the framerates to 30 fps just to display the image onscreen. Unless the HDMI input board is upgraded on one of these new 4K Ultra HD TVs, it will have that limitation
Another thing worth noting is that the current HDMI 1.4 limit of 24 fps in 4K is also in 8-bit color. Ultra HD is expected to bump that up to 10 or 12-bit. With the faster 60 fps rate, twice the data throughput will be needed to push all that — something HDMI 1.4 simply cannot do.
When the new HDMI 2.0 comes out you will not be able to do 4K pass-through with current AVRs since none of them are HDMI 2.0 capable. They simply cannot pass enough data to make it happen.
Also, think about if you actually can see what 4K offers. Here is a seating distance vs screen size chart which shows when you actually get a better picture from each of the formats.
So if you have a 65 inch television you must to be closer than 8 feet to your screen to begin noticing the improved picture. Realistically, you have to sit no more than 6 feet from the screen to be able to confidently say you are enjoying the improved image. To put that into perspective, lay down on the ground and put a mark at the top of your head (assuming you are 6 foot tall), you have to have your face at about that distance from the TV. It is very close. This same discussion happened with 1080, but as you can see with the chart, most people sit in its range due to the larger sized sets people are now buying.
We also need a new video codec, and one is in the works For example, using current technology 3 hours of 4K Ultra HD video uses approximately 3.16TB of data. The new codec can theoretically cut that in half, but that is still over 1.5TB of data and current BluRays are limited to 40GB of storage so new media will need to be developed to sell you a 4K movie. And woe to those wanting to stream 4K content over the Internet or your Cable TV system (though FiOS could do it). These are all problems that need to be addressed before full 4K can ever reach the consumer's living room.
I am not poo-pooing the current iteration of 4K, just saying its lifespan is short and buying now with the expectation of being future proofed for 4K is an act of failure.