Any bulb can last indefinately... just reduce the voltage applied to it, and the sublimation of the tungsten atoms will be slowed to a near stop... of course, it'll put out a lot less light, and the light it puts out will be nearer the 700 kelvin range (blue daylight is 5600, yellow incandescent is 3200)... but it will last nearly forever. There are still 100+ year old bulbs of Edison's burning in his house.

Bren R.