Bulb manufacturers like General Electric says that a total phase out is unnecessary since they expect to have incandescent bulbs twice as efficient as those of today by 2010. By 2012, they expect one that's four times as efficient.
Thomas Edison's light bulb is already 128 years old and much of the technology it uses cannot be improved to a great extent if new materials are not available. In experiments with the first light bulb, Edison used materials like sewing thread for the filament. The photo is from http://news.yahoo.com/photo/070131/photos_sc/2007_01_31t084847_282x450_us_energy_california_lightbulbs