This game is going to have to do a lot of things right in order to compete with GT5. Graphics are going to have to be stellar, racing is going to have to be realistic, the car selection must be large at the absolute least, and the customizations must be equally as extensive.
In addition to all that, they just need the right feel to compete, GT5 and Forza are the monsters of racing sims, NFS comes off as an arcade type of game, so they are going to need to have some impressive improvements for people in the racing sim community to take them seriously.