Edit: Oops didn't realise this thread was 6 years old, LOL. Oh well I'll just leave my reply as is.
I think outside of model-specific issues, most good LCD TVs last a good while. One thing about the older CCFL-lit LCDs is they get dimmer over time, as is the nature of CCFL lighting. Because it is gradual, it'll be hard to notice if that's your only TV, but if not, you may notice it being dimmer against a newer TV. Well not only that, CCFL sets in general aren't nearly as bright as more modern LED-lit ones, not just because LEDs are brighter or because of aging but because many LCD TVs are made to be brighter now, due to HDR.
My oldest LCD set is probably actually my 46XBR8, however that set also probably has the least hours of all the TVs I have except for my two pretty new Hisense and TCL sets, that are only months old. TV is still fine but without any hours on it that's probably not a good indication of reliability.
My sister has an even older one though, a 46V4100 I think it is, from 2009. Now that has a crap ton of hours on it as it has been her main/sole TV for almost that long--so over 10 years anyway. Still working perfectly fine AFAIK. I think it was over $1200 CAD (was bought in a package that had an HTIB and free PS3, for like $1600 I think) back then.
I also have a 40EX40B (very similar to OP's EX400 except with a built-in BD player) in the house which is working fine but again doesn't have a ton of hours on it either. More hours than the XBR8 though. Speaking of dim CCFL TVs I was just using that TV yesterday and was wondering why it was so dim--I cranked the backlight to max and was thinking "this is as bright as it gets???". How modern 4K TVs have spoiled us :laugh: Even the ones that "don't get bright enough for good HDR" are still noticeably brighter than old-skool 1080p sets.
All that said, I keep getting the "they don't make 'em like they used to" feeling about TVs these days. The good news is the "2nd tier" brands (Hisense, TCL, Vizio) are making really impressive sets for low prices. The prices are so good in fact that you probably won't even care should it break in like 4-5 years and you have to buy a new one :laugh:
Buying a 1st tier brand though (Sony, Samsung, LG), you're paying a relatively high price there, even for their lower end stuff--you'd really be more concerned about that lasting I think. And in their lower-end and midrange stuff? Honestly I think they're just fluffing it these days and those sets really aren't all that great, relying on selling their name more than anything. I'm not convinced those sets would be any better for long-term reliability than 2nd tier sets. Still even these sets are not nearly expensive as they used to be, per unit size. Not like we're paying thousands for 46" sets anymore!