A return to the 60 year long  term trend line would take average price to 525K or a drop of another 30%.  Unfortunately market corrections rarely stop at trend lines, the 1974 and 1989 ones dropped 25% below which would take average price to 450K or another 40% from where we are now.  

I would expect that historically low interest rates <5% for the foreseeable future will cushion the bottom significantly.

We are seeing a classic "investment" bubble play out.  People forget that the longer an unbalanced condition exists in a market the bigger and more vigorous the correction.  Still too many people saying "This time it is different".  I can't think of a time where it was.