A Supergirl film should not be filling me with such a sense of dread, but this is where we're at right now, I guess. I love the Superman mythos and Supergirl, but the fact that they feel they can possibly to it without addressing or featuring Superman at all if they have to is pretty alarming. Slightly less troubling but still bad is, if this thing with Cavill somehow works out...they are only talking a cameo? The word "cameo" does not bring to mind something significant.
And these two characters are significant to each other. Clark grew up thinking he was the only member left of his species, and when he gets around to finally meeting others and learns he's not alone...it's Zod and his cronies. Meeting another member of his species who is not only a good person needing guidance but is also his blood relative who knew his birth parents is HUGE for him. From Kara's perspective, she actually grew up on Krypton (or in the Silver Age, on Argo City after its destruction, but still surrounded by a city populous and culture before it too was destroyed) and lived with her birth parents all her life to that point. She experienced Krypton's loss, and believes her entire family is dead until she meets Kal. That is similarly a major event for her. This is not the type of meeting that should be relegated to a cameo or, even worse, an off screen meeting. It'd frankly be kind of insulting. Don't blue ball the audience like that, why should we care about this girl and her familial connection to Superman if the damn film doesn't care enough to actually show it?
If they are worried that too much Superman will overshadow Supergirl in her film, well the sensible thing would be to do a proper MOS sequel based around him meeting Kara with Brainiac as the threat that unites them. If they are not completely confident in Superman himself anymore, market the bad place out of Kara's involvement in the film. She'd likely be the deutragonist anyway. After they see how that goes, spin off Supergirl into her own film where they could get away with only a cameo for Superman or not feature him at all because the big meeting already took place.
As far as these rumors of a Supergirl film set in the 70s, I hope they are not true, because that would be so dumb. If it's set in the DCEU, that would mean Supergirl debuted before Superman. And I'm sorry, I love her, but she's a supplemental/supporting character, not the face of the franchise. You think they would ever have Robin or Batgirl debut before Batman? bad place, I don't think they would do that with ANY of the others, but somehow this may be being considered for Superman.
