For the last couple of weeks, Katie has been the only person not to have been in the final boardroom. Let's look at the previous people who were in this position, to see how they did. May give us some hints as to how she does:
Series 1: Tim (though I'm not sure if he counts, as he was a bit of a technicality - he would have been in the boardroom as losing PM in Week 4, but Adele left before he could bring anyone back, so no one was that week)
Series 2: Paul
Series 3: Simon
Series 4: Lee
Series 5: Kate
JA1: Arjun/Emma
Series 6: Stella (not counting Raleigh)
Series 7: Helen
YA2: Lizzie
Series 8: Nick
YA3: Lucy
Series 9: Jordan
So no one in that position has gone on to win since Series 6, but before that it had happened the majority of years. There have been a lot of runners-up to have done it though.
From the edit so far, I think that the final (assuming that it's a two-person final like last year) will be two out of Katie, Roisin and Solomon, although I really couldn't say who will get to interviews.