I can't say I've seen anything like this site before. Much of it is pure speculation, but it is an intriguing thought nevertheless; the evolution of humanity will ultimately (according to the site) result in our immortality, allowing us to go as we please.
Read through the whole site if you have the time, if not, check out the 2100-2300 years, it's fascinating.
I'm not sure about the diverging paths bit.
And I didn't see any new source of helium, which we won't have in another decade. And is essential for practically all modern technology.
I noticed that bit as well, but I guess they can't cover everything, Sure does make you think though. If granted immortality with death when I wish I have no idea when I'd wish to go; on one hand it'd be fascinating to watch humanity evolve over hundreds or thousands of years, but on the other, devastating to watch everything we know today dissipate. We'd become obsolete, and even more so in the sense that the elders of today are with modern technology.
Also, @DAB: Worked fine in my Chrome, updated to the latest Canary Build.
That book was written many years ago before WW2 and what I found was that any predictions after WW2 seemed to differ from actual events drastically.
So basically although speculation is fun and all no amount of research into anything more than a few decades away could ever prove to be accurate. There's just too many variables.