Let's pretend that somehow the quincies succeeded at winning the first Blood War,killing all the Gotei 13 and even Squad 0

How did Yhwach intend on killing the Soul King? Did he actually have a plan for that?

I think he was concentrated on beating Soul Society first,then thinking about it (especially since Yhwach lost his Almighty so the future was already too misterious to him and for the first time in his life)

Considering that no one would have been left to stop them (and since even Tokinada was able to pull that off), with all the decades of life ahead of them,I think they should be able to either find or create a way. And they would most likely achieve that

What you guys think? Honestly I don't think they really made a plot hole with that,but it was indeed convenient that Ichigo was born in the same period as Yhwach's return (even though in 1000 years of course something was going to change)