Good question, Tammy. I am curious to hear others' opinions as well, but here's my own.
At a very young age (5), I realized that one era of game shows ended, and it's a belief that I stick to today. In my opinion, 1980 is when one era ended and another began.
Here's my take on it......Up to 1980, game shows were quite plentiful and there were a good many on the air. Up to that point, in syndication, there were still some once-a-week game shows on the air (Price is Right, Name That Tune), some twice-a-week game shows (Hollywood Squares, Family Feud).
Network-wise, CBS axed "Beat the Clock" and "Whew!" that year, ABC did the same to "The $20,000 Pyramid", and of course, NBC killed off "Hollywood Squares" and "High Rollers".
Beginning in the fall of 1980, once-a-week game shows were far and few - at least where I lived, MG PM and Name That Tune were nowhere to be found. Both Family Feud and Hollywood Squares went from twice-a-week to strip. HS even packed up and went to Vegas. The games that premiered that fall (You Bet Your Life, To Tell The Truth) were short lived.
That's why, at least to me, 1980 was and always has been a turning point in game shows. I'm not crafty enough to come up with names for the eras, but that's my personal take.