Then there were the SED display technologies which promised superior image quality to LCDs with far lower power requirements than plasma.
There are a lot of barriers, apparently, between the initial proof-of-concept and a successfully-marketed product.
The barrier to SED was primarily lawsuit after lawsuit after lawsuit. By that my the time SED was ready for prime-time, LCD televisions were selling of for chump change compared to what they'd have to launch them at. Combine that with a shitty economy in 08-09 and a nervous Canon and SED for the home was doomed. They're still developing it for commercial and professional use, however, the display technology really is superior.
But yes, a barrier is a barrier. Just because a technology looks promising now, doesn't mean something unexpected won't happen to dash the best laid plans.