Resurecting the dead seems a plausable and 'worthy ' power for the skull/temple machine/macguffin to have, but 'feels' a little similar to the holy grail.
I did at one point think either Marion or Mutt could be killed by Spalko, forcing Indy to activate the machine to 'save' them. But just who the soviets would wish to resurect beats me (some communist sect that worships Stalin or Lenin, Trotsky even!)
The Mayans calendar/belief system focused on 500yr (approx) time periods they referred to as 'worlds' 1st 2nd 3rd 4th etc.
Could it be that this is a device that could be used to end 'this world' early and start another 'afresh' with the Soviets in total control. Shaping the new world to their ideals and values .Thus echoing the cold war schism and nuclear standoff that existed then.
The Mayans also believed that one day there god Quetzalcoatl would return. A way of invoking a God to 'use' or 'control' could appeal to the Russians too, and could create a nice 'backfire' situation in a similar vein to raiders and crusade.
Or, as I earlier postulated in my thread 'the Macguffin' the skulls are Keys or activators to the temple machine (alien origin) which is an EM device with many uses both good and potentially for evil. Another 'power of god' situation, echoing the Ark....
A good reason to have flashback sequences or reason to seek out/revisit the Ark (hence the recent set pics of the warehouse).
Although I dislike flashbacks (or dream sequences & montages) in film. They are the last resorts of poor Directors !
I do hope NONE of this is right, and what they have in hand is truly suprising and original, but it is fun to guess!