At least some work must have started and project must be funded and on track.
Connecting any of these, only considering the main body of the island: Niihau, Kauai, Oahu, Molokai, Lanai, Maui, Kahoolawe, Hawaii
Many of these gaps are very small, <5 mi
You'll be able to travel above water not flying between the countries.
There are a few reasons a bridge between the major Hawaiian islands is unlikely:
Only four islands have a population over 10,000: O'ahu (1,016k), Hawai'i (200k), Maui (164k), and Kaua'i (73k). That's not a very large population to support a mega bridge. Source: https://en.wikipedia.org/wiki/Hawaiian_Islands
The distance from Kaua'i to O'ahu is 74 miles, O'ahu to Maui is 66 miles, and Maui to and Hawai'i is 30 miles; all other combinations are longer distances. Each one of those routes partly traverses open ocean almost 15,000 feet deep. All the islands experience earthquakes and the Maui-Hawai'i shortest path is along the flank of an active volcano (Haleakala). That all makes bridge building challenging. Source: Google Maps measurement tool
The existing population only travels between the islands today by plane. A privately-run ferry system last decade was put out of business due to ecological concerns and a lack of political support for changing laws to allow it to continue operating. A group of people who are more concerned about the ecological impact of a ferry than the benefit of being able to quickly transport their cars between islands seems unlikely to support a much more expensive and ecologically damaging mega bridge. Source: https://en.wikipedia.org/wiki/Hawaii_Superferry
The Honolulu Skyline rail transit project has been underway for 14 years, at a cost so far of $12.4 billion, and is not expected to complete until 2033 (a total of 24 years since inception). The final distance is expected to be about 19 miles, giving a minimum final cost of $700 million per mile. If a bridge costs 5x as much (which I estimate to be low), then Kaua'i-O'ahu would be $259 billion, O'ahu-Maui $231 billion, and Maui-Hawai'i $105 billion. For comparison, the entire state budget in 2023 is $19 billion. I'm not aware of any examples of a U.S. state funding a road project that was 5x or more of its entire annual budget. Source: https://en.wikipedia.org/wiki/List_of_most_expensive_U.S._public_works_projects
If the above objective facts are insufficiently persuasive, I'll add the subjective fact that I'm a resident of Hawai'i and I find the idea of bridges between the major islands laughable. The only reason I'm not placing orders below 10% is because 2040 is a long way away and the world is a weird place.
