Perhaps the Tyrells and Martells will both put their differences aside and join up with Aegon and Connington, that leaves only the spent Lannister forces backing up Tommen's reign, with the death of Kevan house Lannister is good as done. We don't know if the Vale will join in the last minute, but with the riverlands in devestation, with Stannis and Bolton duking it out in the North, it seems the Targaryen dynasty is back.