My 32V Sharp Aquos was 4 years old when I disposed it of last April 2010 - got rid of it because of space issues in my house, not TV issues. My choice was to get rid of either the 2006 Sharp LCD or the 2003 HD-CRT Sony. I chose to keep the old tech TV.
My 32V LG turned 2 years old last Jan., but it has been used primarily as secondary PC monitor (hence, not heavily used unlike the Sharp and the Sony).
My 19" Eizo LCD PC monitor is 6 years old and still remains COLORFUL and sharp despite years of extensive use. It was pretty expensive anyways and covered by maker's 5-year warranty. Too bad Eizo doesn't sell LCD HDTVs.
At any rate, nobody can reliably answer the above question.