Cool. Well, I guess we won't know until we see the credits of MP4. If they reused assets, BN (or whoever was making it) would surely be credited. Keep in mind we have no idea which parts of the first iteration of the game may have been good and which parts were bad. The Prime series is known for it's incredible art direction. If it wasn't up to snuff with Retro's extremely high standards, I'm not sure they would want to reuse anything. I believe Nintendo when they said Retro is starting from scratch.
It's odd to me that so many people are like, "Well, when they said they're restarting from scratch, I don't think it really meant they were starting from scratch."