Is there somewhere in the hundreds of pages of this thread an accounting of what was planned for the scrapped box sets in the Voyager and Leader sizes? I doubt we'll actually see them like we did the three smaller classes, but I'm starting to wonder if an undocumented feature on Overlord was meant to let a redeco pass as a significantly different character, like Starsaber or something. (The jet nose piece can peg onto the chest as armor.)
All we have is speculation on those figures as our best hypotheses point to the latter two boxsets being scrapped early on in planning, to be replaced with the Arcee/Ultra Magnus and Grotusque/Scorponok sets.
And while I'm no industry expert, given the costs that go into designing Leader Class figures, I would speculate that Sky Shadow and Overlord are paired toolings.