Now, I'm not 100% sure of this, but I am certain I remember when Ben signed on for Prince Caspian, he signed on for a three movie deal, including SC. I suspect when Disney jumped ship that contract may have been voided because Walden didn't even know if they were going to carry on.
At any rate, it may very well be Ben's last movie cause the box office numbers thus far aren't making me feel too hopeful about future movies.
But I'm sure, nearly positive, that if they do go on and make SC, Ben will be there. They definitely wanted him for it at one point in time, I doubt they've changed their minds. Especially considering how hard they try to wheedle characters from the previous movies into the current movie that aren't supposed to be there.
At least Caspian IS in SC. And I also do know for a fact that they talked about Ben in old man makeup at one point. I have that in an interview.
Yeah, not too worried.