Agreed.
I also bet you will see Luthor getting ahold of some Kryptonian technology that allows his business to grow ten-fold. Hence, allowing him to be the mastermind behind some other threat for Superman (i.e. Metallo).
I've had some people say they want to see Darkseid but I feel he'd be better kept for a Justice League film in the future. I think establishing Luthor as a character should be part of the second MoS movie but not as the main villain. Have him as the puppetmaster behind some other threat like Metallo or Parasite or Bizarro, etc.
Amazing Spider-man has done this well. Norman Osborn will show up in the second flick but his "presence" is felt all over the first one. Man of Steel 2 should have Luthor's presence at the very least.