I am really hoping to see a final two of Tom and Ian. I think it would be the most deserving final two since ... well, since the show started. If the alliance between Tom and Ian is like that between Colby and Tina in Australia, I think that's what we'll see.
How I think it'll play out (just my guessing, and subject to who wins immunity) --
If the Tom/Ian/Caryn alliance holds strong, Katie and Jenn will be the next two to go. Most likely Jenn followed by Katie. Ian probably takes the word he gave Katie's BIL seriously, so even if Katie goes against Tom, Ian, and Caryn, it's most likely Jenn first. It's possible Ian, Katie, and Jenn could team up and get rid of Tom if he loses immunity. If that happens, though, I'd be surprised. It would take something very major for Tom or Ian to turn on the other.
IF Katie doesn't royally screw Tom and Ian over, Caryn could be next. If Tom and Ian decide that Katie can't be trusted and was willing to switch to team with Gregg and Jenn, then Katie's gone.
Final three time ... Tom, Ian, and Caryn or Katie. Tom wins immunity, it's Tom and Ian to the final two. Ian wins immunity and Caryn's there, it's Tom and Ian to the final two, but if Katie's there, it very well could be Ian and Katie. Katie wins immunity, it's her and Ian if their alliance holds. Caryn wins immunity, most likely it'll be her and Ian because she'll see Tom as the likely winner, although she could take Tom to the final two because he helped her get that far.
Ought to be an interesting next couple of weeks.