This is a cool design challenge that showed up on DJ Tech Tools' blog to mock up DJ controllers. DJ gear vendor Numark is reported to be releasing a controller with a screen. That's kind of interesting, because it could potentially let digital DJs that use them close their computer screen and focus on performing.
While there are CDJs that already have color LCDs to preview deck track information, midi controllers are largely comprised of faders, buttons, knobs, toggle switches, jog wheels, and touch sensitive strips. At most they provide color LED feedback behind translucent silicon buttons, and as far I can tell from what I've read they haven't had display screens yet. Perhaps overall cost for the hardware is coming down, making it possible to deliver screens into more products. Thanks, Moore's Law.
DJ Tech Tools put up some Photoshop assets for its users to imagine what the other existing DJ controllers would look like if they had screens. It's kind of fun watching the DJ community come up with ideas. I see a some concepts that feel over-loaded. Hardware is interesting because more buttons/knobs for dedicated access to functions can be better, but there comes a point where I imagine ease of access to essential functions can be lost when too many secondary ones are added. There's a sweet spot between the minimalist DJ setup and the advanced/expert user that I imagine makes for some difficult product discussions at these companies.
UPDATE: Traktor tease their Kontrol S8.
http://www.djtechtools.com/2014/07/17/what-if-other-dj-controllers-pioneer-native-instruments-vestax-had-built-in-screens/