Oh, there would be tweaks, always tweaks. Pyramid is the same basic game it was on day one, with tweaks (6 instead of 7 items in the front game, different dollar amounts) but the only other difference is in staging, camera shots and host.
TPIR has managed to survive with no real changes, other than the color of Barker's hair. Still, there are tweaks going on - new pricing games over the years, changes in how prizes are shown. In fact, IMHO, one of the reasons for TPIR's longevity is the variety of the show; don't like one pricing game, another is coming in a few minutes.
Match Game? Well, from seeing Funny Money, I think Jimmy Pardo might have done a nice job with it. There, the game wasn't that strong - fun, but not strong - and blew up in the raunchy 90s.
Some games have staying power; some are part of their times. And every show gets cancelled, except for Meet The Press and Monday Night Football. And even those are far different from their early versions, or even from a few years ago.
Change is the only constant.