Kevin Hart - Gilligan
Cedric the Entertainer - The Skipper
Neil Patrick Harris - The Professor
Brian Cox - Thurston Howell the Third
Helen Mirren - Lovey
Mila Kunis - Maryanne
Isla Fisher - Ginger
Some character, maybe Mr. Howell, would need to be a Trump-like villain. There would also have to be a typhoon, or rising tide, that would be a teachable moment so the Professor could lecture about climate change. In spite of your black and gay cast members, there are no trans-sexuals, so the film would be condemned as insufficiently intersectional by woke Twitter mobs. Serious speeches would ensue at the Academy Awards, followed by knowing applause, with a closeup of Tom Hanks solemnly nodding his approval.
I would actually like a Hart/Rock Gilligan's Island. And Cox/Mirren is a pretty good casting too.
I hate the rest though. It rings true. They would absolutely make the Professor gay. They would absolutely miscast both sex pots. Taylor Swift has the look (though I don't like her much) for Ginger. Isabela Moner/Merced is about as close as they'll get to Mary Ann.