The yellow ending is implied to be the most hopeful because even though everyone is wiped out the archives liara creates will give the next cycle the knowledge needed to break free without destroying the relays.
Isn't that odd too, valuing the defeat of reapers and preservation of relays higher than everybody's survival? And all that for the benefit of some unknown future species?
They will ignore the lore about the mass relay tech being totally impossible for them to understand and replicate. And ignore all of the extremely widespread starvation caused by immediate destruction of the galactic supply chain.
From the perspective of someone that wants Mass Effect 4, I have seen Shepard can be brought back to life after being brain dead, burned, and frozen, simply with human technology already available. So I am not worried about him.
A clean slate setting where the existing races reappear with new dynamics because they went nearly extinct is fine with me. So are new races with new politics. (Also, making all of humanity literally descended from Shepard because humanity was wiped out is a take I haven't seen in a game before that might be interesting to explore.)
But a flaccid Mass Effect where you can only explore as far as an FTL drive can take you with a homogenous rogue gallery is a guaranteed flop. See: Andromeda.