It is tempting to approach this question anachronistically. A starting point would be Caliban's speech:
This island's mine, by Sycorax my mother,
Which thou tak'st from me. When thou cam'st first,
Thou strok'st me and made much of me; wouldst give me
Water with berries in't, and teach me how
To name the bigger light, and how the less,
That burn by day and night: and then I lov'd thee,
And show'd thee all the qualities o' th' isle,
The fresh springs, brine-pits, barren place, and fertile.
Curs'd be I that did so! …
For I am all the subjects that you have,
Which first was mine own king;
Postcolonial critics study this in light of subsequent attitudes towards colonialism and slavery, and would suggest that the most just way to behave would be to return the island to Caliban because he is its rightful owner. The problem with that solution is that Caliban has been changed by civilization, and like members of the First Nations or Native Americans may no longer be integrated with the pre-colonial life of the island or able to return to it. Thus one might need to help Caliban reconstruct a new way of island living that synthesizes the natural and the civilized.
The problem with a post-colonial approach is that it is unlikely to reflect the attitudes of Shakespeare or his audience, who would probably agree to leaving him on the island, but mainly out of lack of interest in his future.