So what are your theories on vampire academy's last book last sacrifice?

so i love vampire academy and im dyin waiting for last sacrifice to come out!! i have a few theories on what i think will happen and i want to know what other peoples opinions are and what you think about my theory i think that Tasha Ozera killed the queen and i think that Lissa's sibling is Ambrose i think the last sacrifice will be either Dimitri will either sacrifice himself for Rose by saying he killed the queen or that Dimitri and Ibrahim will bust her out before trial and they go on a mission to save Rose! tell me what you think =]