Yep, IPv4 is history. However, I prefer it because I can't get my head around IPv6. but, What if our PC/ISP does not support with IPv6 by then? sites like Google, Facebook and Yahoo may won't work if we don't using vista or higher. (not sure of other OS-es)
All major OS systems support IPv6 (Windows NT*, Macintosh 10.x, Most Linux Distributions). Your ISPs will do all the work of reassigning behind the scenes and you won't notice a thing.
*Windows NT refers to all Windows OSes that use the NT Kernel (earliest being 2000)