Pick any show on currently, and list how the show would “jump”, you can be as realistic/outlandish as you wish.
House is diagnosed with lupus.
NCIS Shannon and Kelly are alive. They faked their deaths years ago. Gibbs finds them again, but then they are killed by Ari.(who is also not dead.)
Modern Family cousin Oliver comes to live with them, or they get a dog that makes sassy comments only the audience can hear.
They meet the mother.
Supernatural: Sam and Dean find out they have another brother they never knew about.
Wait.
I’m kidding of course, as that happened in an episode called “Jump the Shark.” and was played for laughs initially while later developing to be a key plot point.
More seriously, if either of the boys left the show for awhile, that’d be it. It relies on the two of them being close.
Depends on how she is introduced. They could keep it good by introducing her to the audience but not to Ted. Perhaps she becomes a collegie of one of the other gang, say Robin.
Michael Scott starts a relationship with Angela.
They never meet the mother.
House and Cuddy get together. No wait, that happened.
It turns out that House and Cuddy getting together was just one big vicodin-fueled hallucination, and as we see a sweating House blurrily draped over his toilet coming out of it, in the background Kutner from season five walks out of the shower.
No, hang on, all that would actually *improve *the show.
Breaking Bad:
Walter and Jesse team up with a Gazoo like Fred and Barney had on the Flintstones. The part is played by Verne Troyer in a green unitard and deely bopper.
Jack and Liz become a couple on 30 Rock
Paddy’s Pub moves to France.
Shaun and Gus are forced to, well, jump over a shark.
I hope one of their writers is a Doper and reads this… 
Mythbusters gets religion.
BBT: Sheldon and Amy Farrah Fowler actually engage in coitus, and Sheldon suddenly realizes that there’s more to life than what he’s been doing and becomes a 70’s style horndog.
Don’t know if they could stretch that over the new series extension, or maybe it could be a dream sequence.
They relocate Law and Order to Los Angeles.
OOPS.
That would piss ALOT of fans off! (not to say it wouldn’t qualify as “JTS”)
That’d be AWESOME!!!