When Dickman/Schwab replaced our tires a couple years ago they checked the sensors and at that time they said they should last 10 years, not 5. Ours are 5 years old and doing fine.
My theory is if one fails and you can't get the warning light/buzzer to go off, you can just check the air pressure manually then pull the power to the thing until you get some place when you replace the sensor. I've learned that works well when warning buzzers get too annoying.
Former Owner, 2006 36MDDS
2010 Arctic Fox 22GK Travel Trailer
2007 Toyota Tundra