I've often thought of this. I longed to see Powermaster Prime in the cartoons (besides that horrid guy in the costume).... This is a long way of saying I'd have loved to see the Powermaster concept brought to the series and would've loved the series to continue on many more years. The Powermaster idea is still a good one, and brought about some interesting conflicts in the old Marvel comic.
What do you think of the G1 US cartoon's depiction of Headmasters and Targetmasters?
I thought the *masters were great toy gimmicks, but the G1 US cartoon's concepts -- people in exo-suits that transformed into heads and guns -- was ridiculous. The idea that some guy sitting inside a sentient, battle-ready robot's head, pulling levers and pushing buttons to control in part or in total all of the robot's actions, is somehow more effective in combat than the robot acting on its own is laughable. The cartoon didn't show what a Targetmaster human did when sitting inside a Targetmaster gun. Did he just sit there pushing a big red fire button, hoping that the robot never dropped his gun from 15 or more feet in the air?
The Japanese Headmasters series wasn't very good, but I found its *master concepts -- smaller robots who transform into heads and guns -- to be less absurd.
The G1 US comics weren't consistent with how they treated the concept. In early issues it seemed like the *masters humanoids were physically altered -- turned into cyborgs or something -- although the story didn't make this clear. I never read the G2 comic, but I've heard that Spike (binary-bonded to Cerebros/Fortress Maximus) reappears as a seemingly normal human who just wears a helmet to communicate with his Autobot partner.
Bottom line: *masters toys: cool. *masters G1 US cartoon depiction: stupid. *masters G1 US comic depiction: stupid. *masters Japanese cartoon depiction: less stupid.
Back on topic, I would guess that a longer-lived G1 US cartoon would have shifted its focus almost entirely to the goings-on on planet Nebulos. Optimus Prime, Ultra Magnus and Galvatron would gradually fade away as the stories revolved around the various *masters, and ulitmately the Pretenders, whom I never "got." On the whole my interest in G1 was on the decline by the time the Pretenders came around.