It is argueable that the notion of a 'Renaissance' or 'Universal' man is obselete, and has been since perhaps the 19th century or so; I suspect you could live hundreds of modern lifetimes and still not come close to the relative amount of knowledge it was possible to have in the 15th century.
That said, with extreme specialization being the norm these days, I think there is a dearth of inter-disciplinary and trans-disciplinary thinkers, to unify the vast amounts of knowldege divided within and between fields, and to bring perspective to the almost unimaginable technology mankind will be able to wield in the next 20-40 years.
Sometimes I worry that there aren't enough inter-disciplinary and trans-disciplinary thinkers. Of course, it may just be because I'm around a lot of academics who seem to be highly specialized.
There are limits in human abilities. We actually don't multi-task very well at all. Concentration is key.
This means that the scarcity of time should kill all illusions of the potential to do it all. There just isn't enough time to get good at many things.
If we could fork our intelligence, learn and do multiple things at once, even if only virtually, and then merge the result, we'd get closer to the ideal. Unfortunately, this is still science fiction.
