It's a huge stretch, but I got to thinking; now Marvel can use Spidey in Civil War, could they also use Punisher?
It'd make things more interesting. It would introduce Punisher to the MCU. Also help pad Spidey's involvement in the film. Adds another member to Cap's side of the team. Expand the MCU further too, of course.
This is just a quick thought, but I think there's reason enough to include Frank Castle into the mix of things and introduce him into the MCU alongside Spidey.
I've got nothing beyond this. But what do you think?