The original Double Dare on Nickelodeon could have lasted at least another year. From what I read online, the show was apparently renewed for another season after 1993, but the network decided to reruns as long as they could instead. Also, Marc Summers wanted to spend more time with his family and focus on other projects, which was another factor in the show ending. Still, the show was still popular enough that the live tour continued through 1995, and apparently, a pilot was made for a return in 1995, per TVTropes (although I question the validity of this claim), but the show didn't get picked up.
The $25,000 Pyramid/The $100,000 Pyramid could have lasted until at least 1990. Viewers mail-bombed CBS early in 1988 and demanded that The $25,000 Pyramid return. However, it lasted only 13 weeks before Family Feud replaced it on July 4th. If CBS replaced Card Sharks with Family Feud instead, perhaps Pyramid could have stuck around in daytime and syndication. I think I read on here years back Dick Clark was under contract to host the show until 1990, too, so he would have stuck around.