Warning: Plot Spoilers Ahead 

MTV had the scoop on this one in speaking with Indiana Jones producer, Frank Marshall. He “finally” revealed that - major spoilers are blotted out to prevent any discomfort:

“Well, Cate [Blanchett] is just spectacular, one of the finest actresses working today. She went from ‘[The Curious Case of] Benjamin Button’ to playing the villainess in ‘Indiana Jones,’ so she’s up for anything [...] She makes a great villain. She had a really fun time”

“Ray Winstone [...] plays an archaeologist competitor to Indy. Friend and competitor.”

Meanwhile, Frank has also been talking to USA Today,  revealing some finer points about the development of Indy as an older man and the Crystal Skull powers:

“[Indy's] teaching and having kind of a quiet life,” the producer says. Once the archaeologist is thrust back into danger, the signature Indiana Jones red line tracing across the map will take him to New Mexico, Connecticut, Mexico City and the jungles of Peru.

[...] 

“Indy’s a fallible character. He makes mistakes and gets hurt. He has a few more aches and pains now. That’s the other thing people like: He’s a real character, not a character with superpowers.”

“The theory is [Crystal Skulls] are shaped by higher powers or alien powers or came from another world, or an ancient Mayan civilization had the powers,”