How long will they last?

This varies considerably between manufacturers but usually from 20,000 to 30,000 hours. After this time the plasma screen will only be at around half the original brightness. If you used your plasma screen for 5 hours a day every day it would last over 10 years.

At the end of the plasma screen's life, the screen will be very dull and you will need to replace the plasma screen with a new one. This is one advantage plasma screens have over LCD projectors, which have a bulb life of usually 2,000 hours before replacement.