said by medbuyer:
and I don't think the switches need to be IPv6 ready...
A dumb layer 2 switch, no. Switches operate a step up on the OSI model at Layer 2 so it doesn't care what version of IP you're running or if you are even running an IP-based network.
If it's a managed layer 2 switch or a layer 3 switch/router, maybe. It will still work probably but the management interface and/or routing may not.