It won't be the first time Optimus Prime has died in a TF series and I'm sure it won't be the last but atm there are only 2 eps of season 3 and he's alive (barely) in both of them (unless I missed something). I'm not sure where this new prime talk is coming from, it's possible I missed something but I do know Optimus mentioned the Forge of Solus Prime and Smokescreen went off to try to find it. As for the episode "hurt" that's a season 2 episode where Miko and Wheeljack go off to try and take revenge for Bulkhead being severely injured. I'm not trying to sound like a know it all or anything, it's just I recently got done watching seasons 1&2.
I cryed in this sean.