The most vulnerable components as far as lifetime is concerned are electrolytic capacitors. Standard lifetime is 2000 hours, long-life parts are usually 5000 hours. That's not much, but there' a rule-of-thumb which says that for every 10°C you stay below specified you can double lifetime. So a 105°C cap working at 55°C will have a lifetime of 2000 * 32 = 64000 hours. That's 7.4 years of continuous operation.
Here we touched an important factor: temperature. High temperatures decrease components' lifetime. If you want to go from 24V to 3.3V at 1A in a linear regulator you'll have to dissipate 20W. That's a lot. A switching regulator may be a better solution.

Concerning special protection components I would use a fuse to protect the product as a whole, and a varistor on the power supply input to protect against spikes specifically.

The most vulnerable components as far as lifetime is concerned are electrolytic capacitors. Standard lifetime is 2000 hours, long-life parts are usually 5000 hours. That's not much, but there' a rule-of-thumb which says that for every 10°C you stay below specified you can double lifetime. So a 105°C cap working at 55°C will have a lifetime of 2000 * 32 = 64000 hours. That's 7.4 years of continuous operation. Long-life types will get you over 20 years.
Here we touched an important factor: temperature. High temperatures decrease components' lifetime. If you want to go from 24V to 3.3V at 1A in a linear regulator you'll have to dissipate 20W. That's a lot. A switching regulator may be a better solution.

Concerning special protection components I would use a fuse to protect the product as a whole, and a varistor on the power supply input to protect against spikes specifically.