I find this both interesting and insightful,
DuckSwim. I think there are lots of possibilities beyond the current status quo (which itself is pretty remarkable, IMO). Based on what Ducky has said and my own thoughts about this (I've thought a lot about HI's potential development going forward), the following are some possibilities that I find particularly intriguing and also likely feasible:
The Guest-Babes (HI sandbox limited overlays) - this scenario would play out as the MC being summoned to Joy's office and told that "a guest" (someone from HQ, a friend/associate of Joy, etc.) is coming to the island for a limited stay (3-5 days) and she would like you to make sure her guest has a good time while on the island, and by the way, could you <insert related mini-quest here>. This would involve the MC making appointments with the guest at certain locations at certain parts of the day, making optimal choices, and completing certain related tasks in order to unlock/see all of the guest's content, then the guest would leave. This would be more linear/VN than the general HI sandbox, but when the MC was not interacting with the guest, he would be able to do normal HI sandbox things, like in between the parts of the Amy quest or the new Delizia or Sara quests. This would be a way to use the existing HI sandbox as a foundation and add new girls and content without all of the HI sandbox overhead for each of the new girl "guests".
The Yacht (a second sandbox) - Miriam introduced us to "the yacht" during a walk on the beach (and some subsequent pictures), and it seems a scenario could be created where, after a certain number of days and/or certain achievements have been completed, Joy tells the MC that he is being granted the privilege of going to the yacht for an extended stay. This would then become a new and different sandbox from the island, with the different areas of the yacht (aft main deck, fore main deck, pool, bridge, galley, infirmary, MC's stateroom, girls' staterooms, etc.) becoming the locations in the sandbox. The yacht could have its own set of new girls, and/or "island girls" could come to the yacht (or come and go; the yacht has a helicopter and helipad), and would have its own set of tasks and achievements. It could even sail to a nearby island, which could add locations, tasks, and achievements to the sandbox.
The Rest of the Island (a different second sandbox, limited overlay, or Lab/ankle-style VN) - As Ducky alluded to, and has been mentioned previously by others (myself included), certainly there is more to the island than just the resort and the airport. This opens up some possibilities such as a town/village, hidden caves/beaches, an unexpected discovery, etc., which would allow the present game to expand or to transition in another direction, consistent with
Darkhound's story arc plans.
It's fun to theorize and speculate
(and provide some food for thought), and I'm excited to see how the game development ultimately plays out.