Cassandra dreams of the future might not be true foresight.
They survived the clever hugemoss... Eventhough she didn't clearly see anyone dead in that dream.
We don't know for sure what her dreams are. But considering MC's crew is mostly safe, we can assume it's a warning for the most probable outcome and they need to find ways out of it.
So Cassandra's dream might be different from the mythological Cassandra. But she still has trouble communicating her dreams like the mythological one.