A tontine isn't really a modern thing--they were all outlawed. The only ones I am familiar with are from pop culture and literature. I think they are old world in origin and usually exist within a family or a small group like a fraternity or club of some kind and usually involve some item that can not be split up, such as a fine art or perhaps purloined treasure. The idea is that the last survivor gets the item. That's it. It's not insurance, it's more of a blood oath.