climber said:
Maybe they can make a flash with adjustable light temperature.
Sounds nice but I don't know of technology for that at the flashbulb level. What I'd do is put a thin film LCD in the front, then put whatever color cast you want on it. Effectively it's an electronic gel, and you'd lose a half stop or whatever. Of course that could be done as an add in too, though batteries might make it bulky.
Convenient, but plastic gels are more accurate and cheaper.