Lori, my understanding is that Frid still wanted to play Barnabas; he just wanted to play other characters as well, the way other actors on the show did. And I'm sure that Grayson Hall would have stayed, for a while anyway, even if Frid had left, because she and Sam had a kid to support. Julia without Barnabas should logically have turned to Stokes, but I don't think Thayer David was around enough for that to happen. Maybe Julia would have been killed off (an idea that Sam Hall had suggested) and a new character for Grayson would have been created. But, as I said, I don't think Frid was planning to leave in the near future.
I used to think that they'd set off too many land mines destroying history and thus the "present" that B&J knew, and could never return to 1971. The present would be very different, including the fact that B&J wouldn't even have been at Collinwood in the first place. Now though, I realize that that would never have stopped them. They'd have just ignored they damage they'd done.
It occurred to me recently that there needn't be much of a problem, if the following happened:
1. 1840 Quentin and Daphne have no offspring.
2. Tad dies in the Civil War, bravely falling alongside his cousin Thaddeus.
3. 1840 Quentin dies sometime after 1840 but before 1870 or so.
4. Daphne raises Judith, Edward, 1897 Quentin, and Carl when their parents die: “Great-aunt-aunt” instead of “Grandmamama”.
5. I Ching, possibly even more devoted to Barnabas than Julia is, cleans up the mess created by the fact that Barnabas, having arrived in 1840 via I Ching, leaves via the staircase. Thanks to I Ching, there is a Barnabas in the coffin in 1967 for Willie to discover.
I agree, however, that the writers would never have given us these details.