Currently the Neighbor islands have a small majority (57%) of HI-2, but would have 86% of a 3-district plan. In 2014, about 64% of the vote was from the Neighbor Islands (there is a large military presence in Hawaii, and many don't vote vote in Hawaii, or vote at all).
Then unless there is some affinity between North Oahu and the Neighbor Islands, perhaps the part of Oahu around the Marine Corps and Air Force bases in Southeast Oahu would make sense to let the new 3rd district be even more dominated by non-Oahuans. Still, by 2020, if the trend from 2000 to 2010 in where population growth occurs remains unchanged, there might not be a need to include any of Oahu in a 3rd District. To get equal population, in 2000 the 3rd district would have needed to have 17% of its population on Oahu, while in 2010 it would have needed only a little over 10%. Given the geography, I don't see any reason why a 3 to 4% deviation from ideal district size would be a problem and with current trends, that looks like what will be the case in 2020 (3 to 4% under) and 2030 (3 to 4% over).
