The LEDs will also fail from overheating. LED bulbs don't last long in fully enclosed fixtures that were designed for incandescent bulbs.
If the bulb starts flickering, that's usually a bond wire failure in an LED. When the LED heats up the bond wire loses connection and it will reconnect when it cools down again. The LEDs are in series, so if one fails, the entire bulb goes out. Flickering can also be caused by a capacitor failure in a switch mode supply, but most LED bulbs use linear regulators with a high voltage series string of LEDs now, which also increases the chance of a bond wire failure.
The early LED bulbs that cost a fortune had huge aluminum heat sinks to keep them cool. The few that I had all lasted until the LEDs got dim.