I'm fine with the donor still being Luthor or it ending up being someone else. The smart money says it'll still be Lex though. And that's fine as long as he doesn't go all emo like he did in the previous continuity upon finding out. He's dealing with the fact that all Kryptonian clones go murderously insane right now as it is. Once he conquers that, finding out Lex is his human donor would, logically, not have nearly such devastating impact upon the psyche.
So that's the good news in that regard, in that if we can count on reasonable writing, then if Lex is the donor it shouldn't freak him out that much. The key word of course being if the writing is reasonable.