The key enabling technology for curved displays is that Corning now has a flexible glass that is sold on rolls. It makes a flexible display possible even if printable OLED does not become viable -- which so far it has not come remotely close to being.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.