"After 2010, PSTN will no longer be the main revenue generator in developed countries," report author Malik Saadi said in a statement. "There will be no justification for big operators to reserve a whole network for traditional PSTN voice traffic. This trend will increasingly push operators and network owners to gradually migrate their subscribers from traditional PSTN to VoIP."
Link to news item at Information Week
I bet PSTN phones will become a history very soon. Skype recently introduced free skype out calls to any phone in US and Canada. There will be less use for having a PSTN phone these days. Almost everyone in family carries a cell phone and when they are at home, they have skype, which is much richer than a traditional pstn phone. Remember the PSTN phone still charges $2.99 each for services like Call waiting, Calling Name etc, and charges more for long distance calls.