Just on the basic premise of the thread, if we do Vong stuff, whether it's in Ascendancy or in ICW, it will be made by us; that's always how we've operated. Even looking at Sins, where SoGE, Interregnum and Ascendancy all cover far more similar timelines, we haven't merged teams even though plenty of technical knowledge and whatnot all the time. Mods may be set in the same universe, but the ideas on how to represent that, implement things, and what to design around can be entirely different, as others have brought up in this thread already.
now, something that might happen, is a Sins of a Solar Empire mod that has the stuff from these mods. maybe a extra mod addon 1 day.
This has even less of a chance of happening than a combination of EaW mods. Our main point of divergence with the YVaW team's approach to 3D assets, leaving aside any basic stylistic differences, has been that they use far more polies than we do, which is fine if that's the approach they want to take, but we disagree with it from a performance and optimization perspective. While this is simply an optimization thing in EaW, it actually causes a crash in Sins which has a hard memory limit, making that even less viable. And again, if we want to cover something, our preference is to cover it ourselves.