I expect to see the moon colonized in our lifetimes, not for the He3, but for the iron and silicon ("moondust" is silicon+oxygen). With little more then iron, one can create a very large space station at the L4 or L5 lagrange points between the earth and the moon. Simply rotate the station to produce artificial gravity and viola, you have an environment better then anything on earth. Abundant sunlight for electricity generation and plant growth, whatever weather you want year round, no natural disasters, no population pressures and the ability to go on recreational EVA's in zero gees. None of this requires any fancy technology for anything other then first getting people into space.
Counterintuitive as it may seem, it would actually be cheaper and safer to live in space. Because the moon is a source of abundant supplies of iron and silicon, it would be possible for space colonization to proceed at a nearly exponential growth rate. There's enough of the moon to easily make a space station home for every human being alive many times over. From the time humanity builds its first O'Neil cylinder, it might be less then a couple decades before most people are living in space.
One day, people will look back at the 20th and 21st century and wonder why we couldn't understand that space colonization was so easy.