It's a tough call... I don't see us personally expanding any more than what's there for core. It's lightweight and meant to serve as a foundation for contrib modules. CpILL's inventory has come a long way, and I haven't been able to keep up with it honestly. So really, I don't know and will leave that up to the individual developer. In the long run, you can count on uc_stock being in core and getting updated with Ubercart. I know CpILL is looking to edge himself out of that module's development, so maybe the next step would be for it to tie into the uc_stock API.