Nah, I don’t think it’s radioactiveman. I don’t remember him being there from the very beginning. I also think that it’s probably a little to early for the death of Isaac that Hiro saw/jump experienced. With that aside, I’m still not sure you it could be since, I also don’t remember any of the heroes missing out of Peter’s coma extended vision.
They’ll probably put a twist into the meaning of Peter’s vision. Instead of him exploding, it’ll be him realizing he can retain powers. So far, all the people in his vision are people he’s met or unconciously come in contact with.