Eh, I guess I would give this chance. Obviously, Savage and Fishel have to return. They were the two most important characters on the show, and the storyline for Girl Meets World will revolve around their daughter. William Daniels is an eighty-five year old man. I could see Daniels returning on a cameo basis, but I honestly don't expect him to sign up for a full season.
As far as everyone else goes, I could do without Eric, Angela, and Rachel. Rider Strong should make an appearance or two, because Cory shared a trusted friendship bond Shawn.
I honestly haven't kept up with the cast's post-Boy Meets World career. I remember Rider Strong from Cabin Fever, and Danielle Fishel had a part in one of those of shitty National Lampoon's movies (it was one of the Dorm Daze films, can't remember which one). But yeah, that's about it. I haven't seen anything with Ben Savage or Daniels, and I never had the urge to track down the material.
I'll take a peak at Girl Meets World, because Boy Meets World was a big part of my childhood. Although, it's going to be on the Disney Channel, and their programming is aimed at younger audiences, so I probably won't stick around for a full season.