I find it slightly odd that SideFX aren't part of this. They have worked very closely with Pixar on integrating USD into Houdini in a new subsystem/type of network called 'Solaris' / Lops. It is a very deep and powerful integration too: You can edit USD data using the Python Lop (pxr.Usd API) or even with Vex/Vops (a SIMD-focused language that can be 'written' using 'Vop' nodes that compiles to bytecode and runs (fast) on LLVM.) Makes sense considering how much Houdini gets used to create assets (including at Pixar and for many AAA games as well.) Hopefully the alliance don't make things harder for Solaris! (Autodesk is a direct competitor because of Maya).