[Sethomas]

Yes, but only one fairy can dance on the point of a needle.

As for the oblivion rendering a soul less eternal, I'd say that it doesn't, but the metaphysical reasons thereof are kind of weird. There's a philosophy called eternalism which was rendered into a scientific principle by Relativity, that dictates that all time exists simultaneously from an arbitrary vantage point. That's the main way in which I see the soul as being eternal in the first place; for that matter, today is eternal.