Meh. I’m not sure I’d call the voice-over at the beginning the premise.
Speaking of which (or rather, speaking of Who), wasn’t the original series originally conceived as some sort of educational show, rather than the sci-fi adventure show it wound up as?
The WB network’s launch sitcom Unhappily Ever After was supposed to be about a family after the parents divorced, but they gave up on that and it eventually became Married With Children and a Talking Stuffed Bunny for a while, then they killed the mom off or something, I forget exactly, and the premise changed again.
Alias was originally about a spy turned double agent trying to juggle her college and friends with the job, then they took down SD6 a year and a half into the run, and killed or wrote off the friends and college aspirations, and it was just a show about a spy.
Smallville was about high school student Clark Kent, growing up in Smallville before he becomes Superman. Now it’s about reporter Clark Kent, spending all his time in Metropolis saving people as the Blur because gosh darn it they can’t call him Superman until the show ends.
I don’t think that one quite applies. It’s not as if they could keep him in high school indefinitely. I think they’re within the bounds of the premise so long as he neither flies regularly nor is a public superhero.
It was pitched as Wagon Train to the Stars, which I doubt was about discovering new Native American civilizations. It was always meant to be a Space Western, though the Western part was more in concept than practice. Firefly did the actual genre integration much better.
Roseanne’s gotta count for something here. Started out as a tough-talking but loving wife/mother struggling against the obstacles life throws at her and her lower-middle-class family. Ended (ignoring the finale’s last five minutes) with the Connors as multi-millionaires, for God’s sake.
Admittedly it took nine seasons before the abandonment took place, but when it did, hoo doggies did it TOTALLY go off the rails or what?
I disagree about MASH*. The premise was war is hell, and the doctors must do what they can to save lives and hopefully save their sanity. By the end, Hawkeye temporarily lost his battle but that doesn’t mean the premise changed.
I don’t think it was temporary. I don’t think he ever got completely better, even when he was at home. 
I’m an optimist! (Well, for fictional characters, anyway.) I’d like to think that while he was certanly changed by the experience, he mostly recovered from the whole chicken/bus scenario. Now he’s happily retired after enjoying a pleasasnt, quiet career as Crabapple Cove’s beloved Ol’ Doc Pierce.
The same applies to Dave Sim’s Cerebus - silly swords and sorcery comics parody evolving into complex religio-socio-political satire with some comic elements evolving into ARGH WOMEN ARE ALL BITCHES FROM HELL ESPECIALLY MY EXWIFE ARGH ARGH ARGH. It’s a great example of watching an artist go irretrievably off the rails in the course of 300 comics.
Not really – it was always meant to be a sci-fi adventure. They did have the idea during development that there could be some educational value to it, with stories set in the future or in space being based on current scientific knowledge, and stories in the past based on sound history (and the first companions were a science teacher and a history teacher for that reason) – but it was always meant to be entertainment, first and foremost.
Oops, I see my show was already mentioned above
Since they seemed to have unlimited holodeck resources, maybe they discovered a way to create holographic torpedoes? Hey, think about it: they’d only have to last long enough to be charged and fired.
I never actually watched Felicity. My knowledge of it basically was that it was a show about a college age woman played by Keri Russell; that there was a big controversy when one of the writers of the show, who had claimed she was nineteen, turned out to be thirty-two; that there was another big inexplicable controversy when Keri Russell cut her hair; and that the creator of the show made a joke about the lead character secretly being a spy and then used that idea as the basis for his next series, Alias.
But I read Cracked.com. And they did an article on “TV Shows That Completely Lost Their Shit”. And apparently Felicity was one of them. Apparently in the fourth season they had Felicity traveling back in time. By the use of wiccan magic.
Didn’t Hello Larry really change his job and the general premise of the show around? Between swapping out cast members, that is.
Off the top of my head, Family Matters started off as a reasonably realistic sitcom about a working class black family, and ended with being the amazing adventures of a time traveling Steve Urkel in space.
Apparently the producers had already shot what they thought would be the series finale when the network decided they wanted four more episodes, so they came up with the time travel story arc. The original “finale”, the one that aired right before the time travel episodes was actually good, and tied things up pretty nicely. The actual finale, OTOH, turned out to basically be a clip show with Felicity reminiscing about her past experiences as she tries to go back to her original timeline. It also left a major plothole in one of the characters (or two, depending on how you look at it) inexplicably coming back from the dead.
A few from the 70s:
*All in the Family. *First Mike and Gloria moved, then Edith died. They should have ended the series then, but . . . instead we have Archie owning the bar (with several really bad actors), and some little girl lives with him.
*Mary Tyler Moore Show. *I seem to recall that in the pilot Mary had been divorced. Somehow it became a marriage that never happened.
*Rhoda. *In the pilot Rhoda meets Joe. Rhoda becomes happy and boring. Rhoda divorces Joe. Rhoda remains boring. Show should have been called Brenda.
The story I heard was that some studio executives were worried that viewers might think that Mary had divorced Rob Petrie.
Speaking of The Dick Van Dyke Show, I just realized that six of that show’s nine cast members are still alive. Pretty good for a show which will be celebrating its fiftieth anniversary next year.
It’s my recollection that she was always, in in-story terms, never married and recently un-affianced. Before the show went into production the plan was to have her be a divorcee, but as you say, the studio didn’t want to bring up the spectre of Rob, even subconsciously.
The Doris Day Show CBS 1968-1973
Season one Doris Day is Doris Martin is a widow living on a small farm with her two sons and father.
Season Two. Doris martin now commutes to San francisco to work as a secretary on a magazine. Mclean Stevenson is her boss.
Season three Doris Martin and her sons have moved to SF. She is now a writer for the magazine.
Season Four. The kids are gone. All except Doris from the original cast are gone. John Dehner is her boss.
Season Five no changes.