The C300S will be S35 while the C500S will be full-frame. It's the main differentiator between the current ones recently released.So are these cameras FF or S35? If S35 I assume so are the lenses. Yes?
The lenses will definitely be FF to allow them to be used on both sensor sizes.
Based on the current rumor, it looks like the new stacked sensor design off-sets the smaller pixel pitch resulting from the increase resolution to 8K. So it looks like you gain 8K resolution with the same DR as the current new C300 MIII DGO sensor. Although we'l have to see how the noise turns out, given the higher resolution.
The rumored C700 replacement looks killer though, combining the best of everything: FF, new stacked DGO sensor design, and keeping the resolution at a sensible 4K, resulting in an even larger pixel pitch than the current C300 MIII/C500 MII, hence the rumored 20+ DR rating. It's possible, but let's see it first.