The Census Bureau is planning to discontinue the production of all 3-year American Community Survey data, according to their budget justification document:
"The Census Bureau proposes to terminate permanently the “3-Year Data” Product. The Census Bureau intended to produce this data product for a few years when the ACS was a new survey. Now that the ACS has collected data for nearly a decade, this product can be discontinued without serious impacts on the availability of the estimates for these communities."
See page 110 of 190, or page CEN-106 of US Census Budget estimates for FY 2016.
The elimination of the 3-yr ACS data products must be approved by OMB before it becomes official.