LEDs are already quite affordable. I've replaced every bulb in and on my car with LEDs for literally pennies apiece off eBay. What they need is to start running out millions of bulb-shaped adapters that will work with everyone's existing lights/hardware at home.
Actually I think the biggest issue with LEDs is they are simply TOO efficient, in both size and energy draw. 100 watts actual would utter melt an LED to plastic sillicon slag. A 2-3 watt quality LED dominates a 100 watt bulb's lumen output, and they can be made to produce light of any and every conceivable tone and temperature if wanted, such as matching the soft light if the old school bulb.
Let's hope we can get a nice smoked glass, bulb screw bottomed adaptor soon, that we can open up, plug an LED in its core, and screw in the ceiling or lamp for a 98% power savings.
