In my opinion that is optimistic. These are rough numbers but If the value has fallen 40% from the peak and started appreciating at 3.5% per year in 2012 it would be 2028. If appreciation were a more realistic 2.5% - it will be 2034. It would take a housing boom of 7% appreciation every year between now and 2020 to get back to that peak level. Those numbers only return the value - they would not include any associated costs of maintenance or Realtor fees to sell.
With over 2 Million fore closures in the pipeline, up to another 10 Million foreclosures expected, decreasing real wages, baby boomers needing to down size (or even vacate due to health reasons), Echo Boomers unable to afford college debt - and cannot even think about purchasing a home, and a huge overhang of homes on the market - home prices being back at the 2006/2007 peak level by 2020 is about as real as Santa Clause.