De gea has always been enthusiastic to go to Spain, Madrid to be precise, but I doubt how possible that is right now as Madrid have already bought courtois recently and there is no way they will be spending another huge amount on a goalkeeper soon.
I do not know if juventus are interested in de gea, but if they are, it looks a sound move to me and one that could be tempting to the player, juve are a top top club remember.

Pogba would definitely leave united, I doubt if he is happy playing for united anymore, going back to juve yet again isn't bad and it'll be a great addition, but I doubt if Pogba has what it takes to win the ballon d'or.