If you are in any way associated with networking administration as a pro, you definitely should be attempting to get IPv6 working everywhere, or else the world will catch up on you unexpectedly.
But if you are a mere networking end user, then you don't need to worry for a while. Much of your equipment will slowly migrate via dual-stack to IPv6 and your ISP will offer IPv4 out of your router for years. They may use IPv6 on their backhaul but you won't see this. There's a nice cozy spot inside IPv6 where IPv4 can and will live for many years to come.
For Hardy, it sits somewhere in the middle. Java supports IPv6 now, so some tentative looking into possible adaptions are relevant, but testing it fully requires IPv6 dual-stack and IPv6-only networks. I presume this will become a matter of successive beta releases aimed at the few among us who know what their networks are or should be capable of.
Most PCs with Apple or Microsoft operating systems are IPv6-capable now.