Well, let's assume these lasers are 10x as efficient as LEDs used in headlights. Even if you lost 70% of the light in the process of exciting phosphorus, you'd still have a net gain.
My question would be: are modern headlights really that much of a drain?
Decent LEDs are, currently, about 6x less efficacious than the theoretical maximum of any light emitter, as measured by the human eye. Incandescents are much poorer performers, of course.
In this case, it's then diffused again through a yellow phosphorus lens.
I'm not doubting the numbers in efficiency gain, but I'm having a hard time figuring them out. Seems that there can only be loss from converting this light "back and forth" (but more than likely I don't understand how lasers work).