It's quite astonishing that, of all the Dallas actors, Barbara Stock is getting a new retro article in People (online).
I always thought that the newer characters (Cally, James, Liz) were written out earlier so that the focus in the final episodes would be primarily on the veterans and also to save money to afford the returnees and Joel Grey in the series finale. So it would be a surprise if Barbara Stock, Cathy Podewell, and Sasha Mitchell (and maybe even Sheree J. Wilson) were paid for the entire season despite their absence, similar to Jane Wyman and Ana-Alicia on Falcon Crest.
Liz felt like a replacement for Stephanie, and I can easily imagine the Johnny Dancer story with Stephanie, too. I just don't really see Cliff and Stephanie as a couple; Liz was a better partner for him. Still, I think Lesley-Anne Down would have been a great fit for the show back when Dallas was still really good, while Barbara Stock was more of a fit for the final seasons.