The NEC did add light blue as a permissible alternative a few years ago (somewhere around the 2005 edition, I think). Note that, like the original requirement in the U.K. when introduced, it does specifically say light blue, not just any old shade of blue as often seems to be used across Europe now! And it's only allowed on sheathed small appliance cords, not as a general alternative to white or gray in fixed wiring.
The brown isn't a problem either, since the code doesn't actually require a specific color for the "hot" conductor, only that it be something other than white, gray, or green (or green/yellow). Black is the traditional choice, of course.
Actually, for fixed wiring as well the NEC hasn't demanded specific phase colors since about the mid 1970's, only recommending the traditional black, red, blue which were formerly required, although It would be unusual to find anything else in a basic 3-phase installation (and some places might still demand specific colors by local amendment to the NEC).
Where a larger commercial place has both 120/208 and 277/480V systems in the installation, it's convention to use black, red, blue plus white neutral for 120/208 and brown, orange, yellow with gray neutral for 277/480, although purple is sometimes used instead of orange.
Since 1971, orange has also been the recommended color to identify the high leg of a 4-wire delta system.
