A leader redo of Combiner cores is interesting. Of them, I think Motormaster makes the most sense since he diverged most from his cartoon counterpart. All of the combiners probably have room for more cartoon accurate representation (given the recent trends of Sunbow accuracy we've seen since Siege started). Same goes for the limbs, to be honest, though I'm not sure Hasbro would be willing to commit most a year's worth of Voyagers to limbs.
Bases seem to be a solid "thing" Hasbro's been doing the past few years. Titans themselves a big part, of course, but even Sky Lynx, WFC Leader Prime, Modulators, the whole Titans Return line all had significant "base" element. One of the major features omitted from the Combiner Wars iterations has been the removal of the base modes the original toys had. With a cartoon accurate (if not necessary SCALE accurate) remake in a "slightly bigger than Voyager" size, the combiner junk could be integrated into some sort of "base mode". Might also help justify redos on the likes of Metroplex and such. IE, a "revised Commander scale" take on Tidal Wave might integrate Menasor's combiner kibble into some sort of "dock mode". Or in a Metroplex, the Superion parts might "extend" the more modest Commander into a more impressive city.
That might also prevent Hasbro from using the more limited Voyager slots for limbs, and could spread them out to a couple waves.
I think it'll be interesting to see what Hasbro does, but I'm not sure I'm in for another combiner after Combiner Wars. I've long settled on "good enough", and am not invested in the Combiners to double dip.