Why someone would choose to switch from a well established language to a brand new bleeding edge one is beyond me.
It's like investing in a company; the smaller it is when you throw in your lot, the better placed you'll be when it grows big. Imagine that Go becomes the Next Big Thing five years from now, displacing large amounts of C/C++ code--this guy would then have five years of experience under his belt in the hot new language right as its popularity spikes.
The potential downside is that the language never takes off and you end up an expert in something that no one wants (see also: Lisp.).