Earlier today Sony's Gamescom site listed PlayStation 4 versions of Journey, The Unfinished Swan, and Until Dawn as games that will be shown at the convention. The games have since been removed from the list, but it seems strange that such a thing could happen on accident. thatgamecompany, the developer of Journey, has already brought both of its previous games to PS4 so I wouldn't be surprised to hear that Journey is on its way as well, but we won't know for sure until Gamescom begins in 17 days.
Journey is probably my favorite PS3 exclusive game, and I would be excited for it to get a fresh new audience over on PS4. I don't think I would ever play it again (my first experience was perfect) but if it was crossbuy I might tinker around with it in offline mode to see the upgraded graphics.