Battlefield 4 for PS3 & PS4 what it means for you HD

So according to the info I gained while in Sweden Battlefield 4 is releasing first on PS3 and then PS4 and likely the same for the xbox counterpart. What does this mean to you and will you end up having to buy in effect two games? Will stats carry over? why has no information been given while pre-orders are already being taken? Youtube: http://youtube.com/luetin09 Youtube: http://youtube.com/acousticlabs Twitter: http://twitter.com/luetin09 Commentary recorded with the Blue Yeti