I heard that a fourth TF movie was in the planning, probably heard it here. Well short of a re-boot, there aren't many options other than Unicron & Galvatron entering the fray. Well we all know Megatron is upgraded into Galvatron by Unicron, we know that Galvatron is a raving looney, we know that Galvatron was voiced by Leonrad Nimoy and that Sentinelprime was also voiced by Leonrad Nimoy.
So this gave me my little idea for the Fourth Movie, how Galvatron is created.
The remains of Megatron and Sentinel are dumped to drift in space by the humans, only to be found by Unicron. He uses both sets of remains (sparks and all) to form Galvatron. This could then set the tone for Galvatron's mental instability. (maybe some other casualties such as Soundwave, Shockwave, etc can become Scourge and Co)
I know it's not highly original, but I think it makes sense / works. At least for me.
