Sansa will be the queen. Said this some time ago (and many other people have said the same), but it all makes sense in the end if Sansa and Aegon will rule as Queen and King. I expect that after all things will go batshit crazy (battle with the others), the story will finish when it started (a Targaryan and a Stark falling in love with each other).
Sa niMic said R + L = J is pretty much confirmed, as it is the identity of the BloodRaven.
Also, we don't know if being a Stark is a pre-requisite to warg. More likely, being a northman is a pre-requisite. On both cases, Jon despite having a Targaryan father, still has Stark blood (from the mother) so he would be able to warg.
Rickon will most likely become the new Lord of Winterfell, while Bran will be very important in the end. Probbaly after Daenerys he will soon become the most powerful person in the world and it has been too much investment on him.
Interesting will be the final fate of Daenerys and Jon. Considering that they are the most important characters in the saga, I would be really surprised if either of them manages to survive.