I get the feeling that one of the shields, and it's Vibranium alloy composition, might be linked to Avengers - Age of Ultron. The clips do show the Winter Soldier catching Cap's shield. Does something happen to the original shield, perhaps?
Also, while Ultron was supposed to have been made from Adamantium, I get the feeling that along with the rights to the X-Men films, Fox also has the rights to Adamantium. With that in mind I suspect that Ultron will very likely be made from Vibranium instead.