Its not a threat (you will get charged - no threat about it) :) It has worked in London. As a cyclist I found it was a double edged sword. The roads were quieter in general which was great on the way in to work when no one was in a hurry. However, on the way home was very different and the average speed seemed to go up dramatically. Let's face it. People don't want to make decisions that will impact the planet and society as a whole. I love all these surveys that report that people actually say they would be willing to do things that would be more inconvenient if it would have an affect on traffic, pollution etc. Unfortunately, I've not seen the result of the survey that asks the question "Ok ... when???". Of course the major problem with any of these plans that have a financial incentive in an attempt to force an attitude shift is that it ends up being a user pays scenario, where those with the means will continue to act as before and those without won't.
The only thing unpredictable about me is just how predictable I'm going to be.