It depends on where the growth is; if growth is uniform across the state then Oahu gets another district all to itself, but in the event that Hawaii gets a third district it probably means meteoric growth on at least one of the other islands - most likely the Big Island.
It would be really interesting to see a exclusive Big Island congressional district, I wonder who would all run....
IIRC, nativist sentiment is the strongest on the island of Hawai'i. It'd be interesting if a district based on that island could get a "pro-Hawaii" representative to Congress.