I'm not entirely sure where CA could go with a sequel.
A lot of the greatness and terror in Isolation was down to the unknown. That first time through, when you didn't know exactly what the Alien would do or where it was likely to show up, was by far the best the game had to offer. It was still a wonderful game on repeat play, and still had it's share of terror, but the fact you had some idea of what to expect meant it noticeably lost it's edge. I worry a sequel that just tries to repeat the same formula would have that disadvantage from the get-go.
CA definitely need to mix it up a little if they want another game as good as the first.