I'm not sure if I share all this optimism about the greatness of VoIP. As someone who used to work at "the" phone company way back when and now works on low-level internet infrastructure, I'm afraid we're going to throw away the baby with the bath water if we all switch to VoIP and let the POTS networks wither.
VoIP relies on an unbelievable amount of complex stuff, from SIP clients/servers to QoS mechanisms to inter-ISP peering and so on. It's pretty fragile. (DoS attack anyone?) POTS on the other hand only needs a one-chip DTMF generator and some analog components in the handset, and all the rest is implemented in the central office in operating systems that have been around for a long time and are built for just one purpose, so they're extremely reliable now.
So I'll use VoIP where it makes sense (such as skyping with a friend in Ireland) but I'm keeping my existing phone line too.