Couldn't happen. The game was a product of its' time. Hip-Hop back then wore it's bravado and influences on it's sleeve. DEF JAM was a perfect time capsule, and replacing the rappers with the new era would be disingenuous.
I could see a kingdom hearts style 'kid video' adventure game with the new guys, but the gritty, kung fu inspired, slum-ridden, chest pounding swagger of the old Def Jam games? Only an HD remaster would do it justice.
Considering the legal rights quagmire that EA would have to deal with to get this remade, I highly doubt we'll EVER see an HD remake.
One can dream, though.