The LEDs are rated for over 80,000 hours.

This does not however take into account the individual's usage pattern and placement of the light. One would also have to consider, the overall percentage output, duration per day, average operating temperature, ambient temperature, fan speed, etc.

If you want to replace the LED clusters, you can.
Each LX72xx pack includes 2 clusters. A 7x06 fixture would need 3 packs and a 7x04 would need 2 packs.