The Dell S2718D is the answer. This is a monitor that's probably thinner than your phone: Engadget reports that it's just 6.9 mm thick, as thin as an iPhone 6 ($555 at eBay). (The iPhone 7 ($309 at Walmart) and are slightly thicker.)
Not bad for a 27-inch, 2,560x1,440-pixel resolution screen with HDR support, no?
Did I mention it's not just a monitor? The S2718D might also be a single-cable dock and charge station for your USB-C equipped laptop. If you've got one of the do-it-all ports, you can plug a single USB-C cable into your laptop and the monitor to get a screen, 45 watts of power, two full-size USB ports for your peripherals, and 3.5 mm audio for speakers or headphones.
Mind you, it's not necessarily a monitor for creative professionals who need picture perfection -- Dell says it only covers 99 percent of the sRGB color spectrum, with no mention of Adobe RGB or more strenuous standards. The panel only refreshes at 60 Hz, so it may not be the best pick for gamers. And while that 45W of power should be enough to charge a MacBook, it's not enough for the new MacBook Pro line (which require 61W and up).
Dell says it'll go on sale in the US on March 23 for $700 (roughly £570 or AU$960).
Also see:, also spotted at CES this year.