It is not only in Hawaii, many places separated by a narrow strip of water (wide enough to outrule bridges) have big aircraft flying on them - even if it's 100 nm.
One example is Copenhagen-Odense (92 nm); before the bridge between the two islands there was great air traffic between those two cities.
Another example could be the Caribbean islands.
So it is not only a problem of Hawaii. If there's some way of checking if there is a strip of water dividing the route selected, it could boost passenger numbers.