Personally i think it is more likely that Alfie will die in the spin off and then Kat will return to the Square as a widow, opening more storylines for her.
I don't want to upset Alfie fans but i really think they've had their time as a couple and since TPTB seem determined that they must be together, either they both have to go or one has to die and all indications are that Alfie would get the bullet.
For those that think that no soap would kill a major character off away from the main show, Brookside did it with Damon Grant in 1987.