[xchaotic]

This is wrong. Modern TV follow standard 'bathtub' curve for failures. If the TV hasn't had any faults when new, it's not very likely to develop any new ones as it hasn't got any moving parts and things that wear and tear. The exceptions are capacitors quality and pixel burn-in, but even after 18 years they might work, you just won't like the picture quality.

[nibnib]

Anything manufactured with some process control should follow a bathtub curve for failures. It's the width of the tub that matters. I don't know if LCDs have been on the market long enough to have much data for end-of-life failures (probably not 18 years?) and that data probably wouldn't be publicly available.

It's hard to believe that TV manufactures are shooting for an 18 year mean lifetime. They might work after 18 years, but it is unlikely.