i think it's questionable whether eren died in vain. some people might say he did, because paradise got bombed again and it looks like the cycle will continue (the growth of the crazy growth of the tree seems to say that the power of titans still exists). but others might say that he didnt die in vain because in the end, eren only cared about armin and mikasa and wanted them to be happy/live long lives--which they were/and did, so eren ultimately got what he wanted. i guess it's up to you to decide what you make of it.
the child is either a random kid or maybe a descendant of mikasa or someone else we know. the kid looks a lot like mikasa, so i'm guessing a descendant (since mikasa died of old age and had only one kid, there's no way she could still have a child that young around)
Excuse you but wtf?? I m lost =)))
so you want to tell me that in reality Eren died in vain, because Paraside island faced the war anyway???
Mikasa remaried and it looks like she s with Jean which is cute, but in the end you want to tell me the whole thing is going to happen again??
And who s the child??