Not something that will likely ever be explained...but an interesting (if somewhat geekish) thought experiment nonetheless.
So, Kal L is buried on Pre-Flashpoint Earth 0 (as far as I remember. I haven't actually read Blackest Night but I know he was briefly resurrected as a zombie...I'm assuming his corpsse was re-buried though). And we now know that Pre-Flashpoint Earth 0 had its timeline tampered with to become the New 52 earth...and that with Rebirth, things are slowly beginning to revert back to a state similar to Pre-Flashpoint, at least in some aspects.
Which begs the question - what exactly happened to Kal L's corpse during the course of all this?
In the New 52 timeline, Infinite Crisis didn't happen. Neither did COIE. So, within the New 52 timeline, there's no logical reason for Kal L's corpse to still be buried on Earth 0.
But now, with stuff from the previous timeline slowly seeping back into reality, it begs the question - could the fact that Kal L died on Earth 0 (in the E0 universe rather) and was buried there somehow return? And if E0 characters are slowly remembering their pasts from the previous timeline, would the ones who encountered Kal L someday remember him.
Its worth noting that Superdad technically should remember Kal L, assuming that right now, he's got memories identical to the Pre Flashpoint Superman.
And what about the end of Convergence where Superdad, Parallax, Barry and Kara defeat Anti-Monitor and prevent the merger of earths. So what impact does that have on the Kal L who fought in the Crisis? Did he not get trapped in Superboy Prime and Alex Luthor's dimension? Did he return to the original Earth 2? And yet there has to be a timeline of some sort where COIE happened to explain Earth 0's existence...so is there a Kal L part of that timeline's history?
Once again, however unlikely it is, I am starting to wonder about that theory that Nuperman and NuLois are somehow E2 Clark and Lois...though I seriously doubt it
And what about the deceased Superman of the NEW Earth 2? Does he figure into this somehow?