OK, so we know major (even most minor) characters never stay dead at Marvel. Seems there is not enough talent over there to create really interesting new characters so they just rehash the same old ones.
They can't even keep 2nd stringers like Hawkeye dead. Or really lame baddies like Jac-O-Lantern. So how is Cap coming back?

1. Wanda does some hoodoo-voodoo
2. Mr Fantastic warps reality with a newly created infinity gauntlet
3. Cap wasn't shot. It was a poser with a serious healing factor. Wolverine maybe? This would get Cap's supporters riled up thinking he's a martyr. And give Cap a chance to go underground.
4. Quicksilver makes like Super-Man, runs around the world really fast, and reverses time. (lamer things have happened. Look at the Spidey clone saga.)
5. It was all a dream.
6. The dead Cap was clone ala Clor. Given to the resistance by Nick Fury. Possibly the one that posed as Diamonback a year or so ago.