I like Glau, though.

Think of it this way, through the last three seasons of the 4400, Matthew had told Isabelle that she was special and meant to "Destroy" the 4400. He wasn't telling her the truth. He was simply using this as a means to manipulate her into what she was originally intendend to do, which was join up with Ryland and make the Promicin shots.

During all of this, Dr. Burkeoff was also led to believe that he was special, and was to be the one to "Create" promicin, as he was very much well "respected" in the future. Again this was a ploy by the people of the future who were more then likely promicin users, to get promicin started in the first place.

We all know, Burkeoff did not create promicin, he wasn't even the first person to know about it. The government was. Meanwhile this whole time I believe that collier is the orchestrator perhaps behind the whole 4400 event to begin with. Looking at the vision he had during his sleep, where he took the promicin into him, it looked alot like he was becoming a "Sylar" from heroes type figure. If he absorbed others promicin, would he not inheret their powers as well?

My theory is valid in my opinion due ot the fact that if the 4400 were indeed sent back to stop some sort of catastrophe, then the timeline would change in the future. Meaning that there would never be a need for the 4400 thus causing a paradox. The only logical explination is that it is the 4400 perpatuating their own existance, and perhaps the "catastrophe" is not real, and is only needed for their perpetual survival.