I am surprised in a way that she's not being killed off; it would be very sad, but they couldn't split Jack and Vera up, so if Bill Tarmey wants to stay it seems the best option. I'm surprised he's staying as he is in poor health himself, and was talked out of leaving a couple of years back.
Perhaps Vera could get ill and go to Blackpool to stay with the Hortons for an extended period of convalescence - sea air and all that. I know it sounds a bit Victorian, but it would make more sense than the marriage ending. That way Liz Dawn could do a few episodes at Christmas or something.