So basically, ABC is giving the writers/producers 3 years to come up with some spin-off ideas. You KNOW there's gonna be talk of doing a spin-off. The most obvious one--if the surviving main characters ever get "rescued" or manage to leave the island, what will their new life be like? Will they keep in touch or will they go their separate ways? Will uncanny events and coincidences and maddening plot devices continue to thwart them?
Also, I'm sure there will be a few "prequel" spin-off ideas floating around. For example, yet another doctor/hospital show starring Jack and his estranged father, and their relationship. Or maybe a show about the original Dharma Initiative project? That would be interesting. I also think they could write a script for what happened outside the island after Oceana Flight 815 went down--loved ones trying to search for the survivors, almost losing hope before Penelope convinces a few that they may be stranded on a hidden island somewhere...then searching for them.