Yeah ... I’ll be looking for it! ... :-) ...
Even retina displays are overkill for most content on the internet and for media consumption. 4k tablets, or even 4k PCs, would be “way” overkill. Rendering very high-resolution photos would be about the only meaningful application right now or in the near future.
However, the iFanatics will eat it up, and Apple will be credited with “innovating” once again, and the stock price will hit new highs, and sales of the 4k devices will be in the multi-millions in the first week. And all of it for nothing more than Apple wanting to create a new sales cycle of their iCrap, which will still not be very capable, other than for media consumption.