Cute, but... Grammatical errors.
A sentence starting with a number should always be spelled out.
The second sentence needs a comma or period after "pixels".
Now in 4K. Four times the pixels. A billion more possibilities.
A product's success can be affected by grammatical accountability.
Apple's marketing would more that likely leave the "now in 4k" part entirely off (since it is still not a term the general public is vastly aware of). They generally like to keep their slogans around 2 sentences. The first describes the specific product feature and the second is some sort of hyperbole, loosely based in pun or word association.
If they were to include the 4k statement, it would more than likely go in the subtext that describes the product in further detail. An example might be:
"With a native resolution of 3996 x 2160, the all new iMac delivers 4k video in a stunning, glass and aluminum package, featuring our most powerful graphics processor yet.