I don't see much need to suddenly make an island interesting if you're going to shut it down anyway.
I would assume the point would be to give the player's losing their continent a reason to stick around. I was around when they sank the last island, but since I didn't play there I have no idea how many players immigrated, simply deleted, or stayed around to sink.
It would be more work than a simple reset, but if it was going to retain players, then I'd think it'd be worth it if player retention and a dwindling player base are a part of the game's problem.
