I think that Dumbledore will challenge Voldemort and either die or be seriously injured, as in a coma.

Everything in the books points to Harry using his love for others to defeat Voldemort.

I am not sure that I trust Dumbledore. There is something going on with him that I do not trust. I get the distinct impression that he has sent more then one letter to Petuna, otherwise his howler would not have said "remember my last". Clearly he hired Trelweny in order to shield her from the Death Eaters, which is why he kept her at Hogwarts when she was fired. I am wonder why he kept Hagrid on. I am guessing that there is a motive that we have not heard of yet.

My gut says that Lupin returns to Hogwarts next year. With the return of Voldemort, Dumbledore will be able to do pretty much what he wants to at Hogwarts. He knows Harry is going to need guidance and probably no longer fully trusts Dumbledore. Since Harry trusts Lupin, Dumbledore will bring Lupin in to help Harry.

Harry is going to be really angry, probably depressed and things are going to look bad.