Martin Rees suggests leaving human space travel to private centibillionaires.

The advantages he suggests make sense, but I see a danger also: that the centibillionaire might organize a space settlement as per own personal demesne. If only 50 people can go, it won't be hard to find 50 people who want it badly enough to yield to that.

I think Rees's equanimity about the prospect of human descendants so drastically different from us is misguided. Unless it is so different that conflict is impossible, I think that difference would lead to war, or else complete subjugation of our kind.