It is very unlikely that a single ASEAN currency could be introduced any time in the near future. The tremendous problems being faced by the euro zone in Europe will serve to deter any attempts to create a single currency for the ASEAN countries.
In Europe, the major problem is the fact that some countries in the euro zone are much richer than others. The countries also disagree on economic policies that affect the strengths of their respective economies. The ASEAN countries would have this same problem. For example, Singapore and Brunei are in the top 10 of richest countries in the world per capita. Meanwhile, Laos is number 177 on the list and Cambodia is number 187. These are some of the poorest countries in the world.
Such huge differences in economic strength will prevent the creation of a single currency.