Eh. It usually takes a generation or two before the holdouts are completely gone. <img src="/images/graemlins/smile.gif" alt="" />

The goal is to convert energy into photons with maximum efficiency. Heating a wire until it glows currently (heh) has two advantages: The emitted spectrum is close to sunlight, so it looks good, and it's possible to dump massive amounts of energy into it to increase the brightness (with horrible efficiency). The only other advantage is that it's technologically simple. That's it... Once a replacement comes along that produces the same spectrum at the same or greater brightness, and does so more efficiently, incandescents are dead.

What's less clear is whether the replacing technology will be LEDs or something even more exotic. Early work with quantum dots suggests it will eventually be possible to tailor the output spectrum and have near 100% conversion efficiency. Sweeeeeet. <img src="/images/graemlins/smile.gif" alt="" />

Of course incandescents will still be around. How can you reenact the 20th century if you don't use exact replicas? <img src="/images/graemlins/smile.gif" alt="" />