The goal: reduce carbon emissions quickly.
40% of people driving 40% less
40% of people using 40% less electricity and natural gas
A 16% across the board, non-commercial energy reduction.
If the savings from that were diverted towards building renewable power plants, then theoretically nothing would change. Things would just shuffle around a bit. Of course we will need a carbon tax. Some people will be paying more and some will be paying less. That's unavoidable, but the theory is true. It's not a new tax if we are making the carbon savings. The idea of it being a new tax, one in which people will have to work harder to pay, is part of the whole problem with climate change in the first place.
The way the 4040 plan works is by drawing the national attention. If Portland can save significant power during the Move the Needle event, then it's theoretically possible to bring the conservation idea to the national level. If we had a national leader with this message, the people that want to do something about climate change would be organized into action. It can happen quickly. We don't have to wait for laws to be passed. If we are organized and taking personal action, we'll draw attention and then passing laws will be more probable. And we'll be fighting the problem at the source at the same time.