Personally, I believe that, if she does appear, Lex would find a way to take away her Prometheus powers and use the technology to construct the famous Green Power Suit from the comics. With Lana being back human, everything could play out as it's supposed to be. Since Clark and Lois are strongly in love witheach other and engaged, Clark would no longer have his long-lost feelings for Lana thathe used to have and Lana could accept them being friends. Now, Pete Ross returns in the comic, he and Lana grow closer to the point where they eventually get married just as their comic book counterparts.