Well I've been thinking of the potential plots for the sequel and came up with two. 1. Origin of the Allspark - The Transformers themselves don't know where it came from or if there are any objects similar to it. 2. The defunked Sector Seven had more than Megatron and the Allspark in their basement. We know they've been experimenting in creating life from the Allspark. The Allspark's energy as we've seen can be extracted so who is to say they haven't extracted a load of energy before the TF incident. Not enough to bring Cybertron to life but enough to build a new army.