A glimpse of the future of the 30-year mortgage can be seen in its correlation with the 10-year Treasury yield. It was only several months ago that the industry was gawking at 4% mortgage rates, with rates now inching closer to 5%. Per Calculated Risk:

Currently the 10-year Treasury yield is 2.82% and 30 year mortgage rates are at 4.58% (according to Freddie Mac). Based on the relationship from the graph, the 30 year mortgage rate (Freddie Mac survey) would be around 5% when 10-year Treasury yields are around 3.33%.