The timing for the TV Academy announcing Thursday that it would combine lead and supporting acting performances for longform programming into the same Primetime Emmy categories beginning in 2013 might seem odd, given that miniseries “Hatfields and McCoys” broke basic cable ratings records earlier this week.

But the decision, rendered official by the Board of Governors of the Academy of Television Arts and Sciences, reflects a larger trend that reality and nonfiction programming simply is taking a bigger share of the television landscape.

“Since 2001, when we first had the reality breakout from nonfiction as a separate category, there has been an increase of approximately 20% in the total number of awards,” Acad senior awards veep John Leverence told Variety. “So there was concern there was a trend in proliferation.”

In contrast, despite periodic ratings highs and critical accolades, the area of miniseries and movies has been in retreat, a phenomenon that was acknowledged most notably when the two programming categories themselves were combined last year.

“It’s one of those situations where you have a legacy genre with (longform), and the Academy does want to continue to recognize those achievements — but on the other hand you take a look at expansion on reality side,” Leverence said. “The awards structure tends to expand or contract with the expansion and contraction of primetime programming.”

“There’s always the concern that awards inflations will degrade the currency and the value of the Emmy. The Academy is ever vigilant in terms of proliferation. It wasn’t something that came out of the blue.”

Each of the two longform acting categories will have six nominees, compared with five each when there were four categories — meaning that the total nominations for acting in miniseries or movies will be cut from 20 to 12.

Notably, it was the performers peer group that engineered the recommendation, as part of an Academy group known as “the anomalies committee” that explores category additions and reductions as part of a general review.

The committee has made 19 recommendations, of which this consolidation was the first to meet final approval. A possible alteration in the awards composition for children’s programming is also under consideration, with the remaining 17 suggestions on hold for now.

The consolidation would on its face seem to make it difficult for any supporting actor in a miniseries or movie to earn Emmy recognition, though that could still vary year to year. In 2011, Barry Pepper of “The Kennedys” and Guy Pearce of “Mildred Pierce” won lead and supporting mini-movie acting Emmys, as did Kate Winslet of “Mildred” and Maggie Smith of “Downton Abbey.” (“Downton,” coincidentally, is moving into the drama races this year.)

The change won’t affect this year’s Emmy contenders, but looking at them can give a hint of the effect the consolidation will have next year. Lead and supporting actors in miniseries and movies year include such possibilities as Kevin Costner and Bill Paxton (“Hatfields and McCoys”), Benedict Cumberbatch and Martin Freeman (“Sherlock”), Idris Elba (“Luther”), Woody Harrelson and Ed Harris (“Game Change”), Dylan McDermott (“American Horror Story”), Bill Nighy (“Page Eight”), Clive Owen (“Hemingway and Gellhorn”), Dominic West (“The Hour” and “Appropriate Adult”) and Ben Whishaw (“The Hour”).

Potential actress nominees in minis and movies are Connie Britton and Jessica Lange (“American Horror Story”), Romola Garai (“The Hour”), Nicole Kidman (“Hemingway and Gellhorn”), Julianne Moore (“Game Change”), Emily Watson (“Appropriate Adult”) and Rachel Weisz (“Page Eight”), as well as Patricia Clarkson, Rosario Dawson, Lyndsy Fonseca, Ginnifer Goodwin and Jeanne Tripplehorn of Lifetime’s anthology telepic “Five.”

Another consequence of the Acad’s decision is that the number of awards categories on the primetime broadcast will be reduced next year from 25 to 23. That would provide the opportunity for two awards categories to move from the earlier Creative Arts Emmys to the main kudocast, or for the producers to develop more non-presentation segments.