I assume they'll recast, which is unfortunate, because I really like the current actors they have in the roles. Cait and Sam are both in their 30's so they're already fairly older than their characters in the first two books, but I don't think I'd buy them as parents of a 20+ year old a few seasons down the line. Honestly, I wouldn't mind if they departed from the books and stayed in the 1940's/1740's time to deal with Claire's reappearance, but I also never got into the later books, so the new cast of characters don't appeal to me.