New QM (Qualified Mortgage) rules will shake the market as they initially come out in January 2014. But quickly lenders will adjust, and it should have little impact in the overall market - other than to make it more expensive, and make it take longer to get a mortgage loan. (Nice job Barney Frank, Chris Dodd, and the CFPB)
A bigger concern in the short term will be when the FED stops, or reduces their ongoing purchase of mortgage backed securities, which has been artificially keeping interest rates low.
As we progress it to early and then mid summer 2014 - one should expect the benchmark 30-year fixed to be in the mid 5% range. While historically that is an awesome interest rate, whenever we see rates move up, we tend to have a 6 - 9 month drop in purchase activity as buyers become disenchanted with the higher rates. After awhile, those potential buyers accept the reality, and new buyers getting quoted the 5% rates just accept it from the get go.