It was a joke based on the running gag that no matter what, Mr. Feeney was always a teacher of sorts in Cory's life. He was his elementary school teacher, then he was his high school principal, but still taught occasionally. He retired and then attended Pennbrook where he eventually became a professor there as well. I'm fairly positive he never actually retired and he remained a professor for the rest of the show.
If you mean after the show, I'm assuming she just led a normal life. If you're referring to the episodes where she was practically non-existent, they switched actors and she eventually returned, only this time much more sarcastic and witty. She was in a bunch of different episodes, but never had much of a role. She was even in the final episode when everyone said their goodbyes.
Don't forget that they quasi broke the fourth wall when the new actress took over the role when she said "That was the longest time out I've ever had!". That scene always killed me lol
But I hope they make this. I used to wait all week for TGIF and Family Matters, Boy Meets World, and Step by Step (wish they would put that on dvd all ready). One of the few good childhood memories I have.
Reminds me too, I need to finish backing up my dvds of Boy Meets World. Only have ripped the first 3 seasons. Thank god Best Buy had the entire series for like 7 bucks a season last Black Friday!