The 84" TVs are likely to be coming in bigger quantities soon as some older 42" capacity gets either completely or partly repurposed to making 84" sets. (You really need very little capacity to move over, since demand for TVs that big is really small and capacity for TVs that small is really quite gigantic.)
110" will follow, but again, the bigger issue is tiny demand, not ability to create them.
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.