Most plastic cups tend not to degrade, just sayin'
But in all seriousness, the lifetime improvement even over the past several years has been really substantial.
The issue with OLED lifetime is tricky, though. We're not talking about the sort of lifetime where it works for a while and then stops working. Lifetime in the case of OLEDs means a gradual, exponential falloff in the brightness for a given amount of incoming electrical power. So while your monitor may be nice and bright when you get it, two years later it may be half as bright. That's not acceptable in a consumer product, and the rate at which it falls off has been the target of research.
What makes matters worse is that brightness itself plays a role in lifetime - the harder you drive the OLED, the faster it decays. Which means that nice, high-brightness computer displays have a tradeoff between the brightness that we want and the longevity that we also want.
Even worse still is the fact that the different colors
of OLEDs have different decay rates. The red has the slowest decay, green faster, and blue fastest. This is especially bad for a consumer display, because it means that not only do you have a brightness drop, you have a color shift as time goes on. Sure, you could compensate by doing color recalibration periodically, but that's not really a solution.
This isn't meant to be a doom and gloom post, however, as they have been making real progress. OLEDs in mobile are getting to the point of being pretty reliable and very common. This is partly because mobile typically doesn't have as much screen uptime as a desktop display likely would, and the lifetime clock only ticks when the display is on rather than a set amount of time. As far as desktops and tvs, I expect a significant transition over the next several years.