I would say there’s a difference between reworking a show and a logical progression.
For instance, All In The Family couldn’t stay the same. They couldn’t have Mike in school forever. Once Mike graduated the show turned into a typical sitcom (OK a bit edgier for its time), with Mike and Gloria becoming the wacky neighbors. Notice how Irene and the Jefferesons were no longer there by then)
The premise of the show was Archie was the typical white middle aged man and the world was changing around him and he didn’t like it. It was the CHANGE of the status quo that really bugged Archie not those around him.
For all those calling Archie a bigot, he was opinionated, but he freely mixed with everyone something a real bigot wouldn’t even attempt to do.
As for Roseanne, the last year was done that way because it wasn’t suppose to be. The last year was suppose to end with Dan having a heart attack and dying. Then the network conviced Roseanne to comeback for one more year and she decided at that point to go wild and do what she pleased.
In a similar type thing Unhappily Ever After was supposed to be a starring vehicle for Stephanie Hodge. But the other cast memebers kept stealing the show. At one point she was written out (killed off) and brought back. The last season she was out again, but that was done specifically as Nikki Cox who played Tiffany was signed to star in her own WB show and the network wanted to use the last year of Unhappily Ever After as a way to build her up so her new show would sell
Rgarding A Different World, Lisa Bonet got pregnant and the writers were at a loss to explain how Denise could be pregnant. So they wrote her out and she was supposed to come back after the baby was born. To do this, new writers and a new producer were brought in and what started out to be a minor edit turned into a major rewrite. Denise was suppose to come back to the show, but by then it had left her behind.
I would say Family Ties was driven by Michael J Fox, but he didn’t quite take it over. At the end there were still many, many episodes centering around Mallory, the parents, Jennifer and even the little kid. I will give you Fox was the effective star and the reason people tuned in, but he didn’t overshadow everyone like Fonzie on Happy Days
Shows like Happy Days are common where a character breaks out. Another example is Two Close For Comfort, which was about an overprotective father and his two daughters. Then JM J Bullock (as he was billed then) came on for a one time bit part and had instant chemistry with Ted Knight. Knight and Bullock were so good together.
Another example of this is Reba. It changed but basically that was because no one really knew what Reba McEntire was capable of. Could she act? Could she do comedy? Park “Empty Nest” Overall was cast to provide comedy if Reba to back her up, but clearly in the first five or six episodes no one saw Melissa Peterman would break out. In the first episodes Peterman’s protrayal of Barbara Jean was all over the place, being Christian, the other calling her BJ (sort of a weak joke). But once Peterman and McEntire were put together, well those two just clicked. It had been a long time since any two females played comedy off each other as those two did.
What should have been a minor annoying character, Barbara Jean, turned into central element of the show.
So I think you have to differentiate between natural progression, early on reworks and things like unexpect chemistry.