Really? There's a far bigger gap between 1080-1440 than 1440-4K. The latter really makes 4K irrelevant till the prices plummet to the current 1440 price range. At the moment it's small gains at extortionate prices.
Sorry, but you got it backwards. There is a bigger gap between 1440 and 4K than 1080 and 1440. A much bigger gap.