The successor to the P6 line is coming and its name is Pentium 4. If you don't know the details of the Pentium 4, we strongly recommend you read our Pentium 4 Unveiled article here. We have one additional piece of information to add though, which we first brought up in our recent Intel Developer Forum 2000 Show Report.
Intel's reference designed Pentium 4 platform will require a new form of case and power supply described under the ATX 2.03 spec. This new case and power supply design is needed for the Pentium 4's high power and cooling requirements. On the positive side, there will likely be a way to modify your case to take a Pentium 4 while still replacing your power supply.