From reader scuba:
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one thing not addressed is that what results in burning out an incandescent bulb is the on-off cycling. that does not apply to a bulb that has never been turned off, so there is little validity to how long such a bulb would last under norman househole use.

more proof how easily human minds can be mislead with only partial truths.
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MrF replies:
I absolutely agree that these bulbs would have life-span issues, and would probably not last much longer than the current late lamented incandescents, while almost certainly being more expensive, even if the design and manufacturing issues can be ironed out. I'm mainly going with LED bulbs at the moment. I hate the CFLs.

As a side note, I'm seriously considering changing my RMN agent name to Norman_Househole.

And about that bulb that has lasted 100 years, it has the old Edison-type carbon filament, not tungsten. Those are tricky to make (from charred silk thread I think), and quite fragile, but a good one could last a really long time. Also that particular bulb is thought to have a much degraded brightness relative to what it would have been originally.