FWIW, I think we tend to try and fit things into prophecy to keep to a time line. No question the day will come and it sure does seem like it will be sooner rather than later.
Now it remains to be seen whether we, in our limited human understanding, have calculated things correctly, but, going by what we've been given in Scripture, it's pretty natural to do the math and, taken as a whole with all the other prophecies being fulfilled every day, to believe that 2017 may be the end of the generation Jesus spoke about.