I am hoping for a season 2 as well, because the main story line wasn't even tied up. I hope the mains won't lose their intrinsic personality and don't become cliches of themselves. I like their everyday man/woman turned heroes.
I'd also love to see the same back team back: I'd miss Mr Gi, Chief Joo Chul, Wa Sook etc...and especially the chicken guy hacker. Unfortunately, I doubt they'll show up and that makes me sad. I like seeing known characters in a new season!
I guess it it will all depend whether Go Hae Ri is still in touch with them or has completely gone solo. The villains are coming back, that's for sure, and I love that they are clever, rather than being stereotyped "too cruel to think". Edward is one cunning fox, he was a great match to Joo Chul IMO (more than Gi who was supposed to be so smart but ended up...not so).
I would also hope for the second season to end properly rather than have a season 3, and with a happy ending. A proper one, all pink and rosy after the many deaths and hard times. Baddies lose, goodies win. A proper relationship between the leads. Friends reunited. Justice done and dusted. I'm not hard to please!