Perhaps the funny case is the EZ-Bake oven, a toy that has been out for decades. It uses a light bulb as a heat source. It doesn't bake very well, but I'm certain it will be a whole lot worse with a CFL.
A more serious use of incandescent light bulbs is their use to warm eggs and chicken hatchlings for chicken farmers. When these bulbs cannot be sold anymore, where will the heat come from?
Another legitimate use of a light bulb is as a true voltage indicator (that there is true voltage, as opposed to phantom voltage, between a pair of wires). I'm sure a properly built tester can do this as well (a gang of resistors and some indication such as LED, meter, or beep).
There are many other cases where light bulbs are used as a source of heat (a function for which they are actually quite efficient at, wasting very little of the energy in the form of radiation at light wavelengths) or as a cheap dummy load (let's see if this 200 main breaker really kicks off within 20 minutes at 250 amps). Of course heaters can be used to make such a load, too.
Maybe we need to create a "heat bulb". There are such things as infrared radiant lamps. But those don't work so well in all cases. What is needed is something in the traditional light bulb form factor, using the same style bulb shape and the same socket. But instead of being designed with a filament that tries to emit a fair amount of light, it should be aimed at more heat. By operating at a lower temperature, very little light can be emitted, and more infrared will be available. A longer thicker filament should do the job, and have the added benefit of more durability and longer life. They would, of course, be more expensive due to the limited market, more extensive construction, and lower rate of replacements. It should be allowed on the basis that it would be so ineffective for lighting purposes that no one would consider buying them for that reason.
Now we just need to come up with some better lighting technology, too.
One of my Maglite flashlights had a bulb burn out, again, and I had no more replacements (each flashlight came with one in the back end). So I picked up one of those LED modules that fit it, at Walmart. I notice the light does have a smoother projection pattern, apparently due to the more uniform construction of the LED containment, as compared to the cheap glass containment of the bulbs. The brightness was about as good as before (so hopefully this means the batteries will last longer). The color, however, is still awful. The white balance is a bit on the blue side. But it is a split spectrum (non-continuous), and that makes it harder to focus when that is the exclusive light source. It's fine for most uses a flashlight is needed for (seeing where you are walking at night, annoying the neighbors by shining it their windows, and cracking the occaisional burglar over the head). So I'll probably replace all of them with LEDs as their existing bulbs burn out. I might go ahead and buy a couple of the LED replacement modules in advance.
I'm still considering build a test light box using an array of LEDs of a variety of different wavelengths that could potentially emulate a nearly continuous spectrum. I've seen 22 different wavelengths, and about 16 of them seem to be good choices for a broad range of wavelengths to use. Then it would be a matter of balancing the intensities to level each of them and get a reasonable white light with lots of tiny peaks instead of a couple big ones on either side of a huge spectral gap.
I still do plan to stock up on incandescent light bulbs in the 15, 25, 40,
60, and 75 watt ranges, as well as 12 watt and 18 watt low voltage (12V) halogen lights, and a variety of PARs.