In normal use, set up correctly, longer than you would likely keep it as a main display. ie 5yrs plus. Most likely it'd still be going at but I don't know what the wear rate is on the different phosphors. You might need calibration every 3 or so years to keep it all tip top
I never heard about this on a plasma before. How is "calibration" achieved, and is it always required after a certain level of usage? How can you tell if your panel requires it, what are the noticeable effects on PQ? I have a Panny Series 4. Many thanks.