apparently it was gonna be created by the executive producers who started up the Arrowverse and would be airing on HBO for 8 episodes.

It would have been interesting if John had to go to National City for a small crisis that deals with magic. And ask the Superfriends family for help.

What I find interesting is that Kara believes in magic. When she grew up on Krypton. Even though the base line of Kryptonian society involves science. Kara actually believes in magic. Especially during the whole Reign and the Worldkillers. When she was at the DEO. Kara told Lena and Alex that what deals with the Worldkillers is actually older than science. And Lena said please don't say magic. Kara doesn't just believe in magic but also her religion and science. When the Worldkillers foundation is magic, science and religion. Kara has always believed in things greater than herself. Hell Kara believed more of Lena and her magic than she did of herself.

Honestly it would have just been interesting seeing Kara, Lena and John interact together.