I know that it was a different studio who made Fallout NV, but I really am hoping that somewhere in Fallout 4 there will be a NCR Ranger helmet and coat, or at the very least, a reference to the NCR's existence. I really, really like that helmet.
Anyway, what are some things you would like to see carried over from other games? How about Easter Eggs? The female PC voice actor in Fallout 4 was the voice of Jack in Mass Effect 2 and 3, so I think it would be cool to see some sort of reference to that in the game. What would you like to see?