Seeing how current events are unfolding, my prediction for the future of the main trio is that Brandi will end up being a kind of Gina (I even think that at some point, if her children aren't interested, Gina herself might encourage Brandi to run the resort for her). It's clear that Gina wants Brandi to be like her in many ways.
As for Dylan, I see him as the future Master of the island, with Camilla as his wife and also a Master alongside him.
And I see Kelly as a future Ann (Emily's mother), serving to relieve the horniness of everyone on the island, men or women, as we saw with Ann several episodes ago.