Drivers ABI, being micro-kernel based, even if everything is kind of bundled together, subsystems talk over in-kernel RPC (LPC), nowadays drivers and critical kernel subsystems are sandboxed on their micro-vms, hyper-v is a type 1 hypervisor (Windows runs on top of it when enabled, is just another guest), many kernel subsystems have long adopted C++ (hence VC++ /kernel since Vista, and Windows Implementation Library, a set of C++ templates for kernel, driver and userspace resource management), async IO since Windows NT early days, COM as OOP ABI (even if tooling is somehow clunky), subsystems just like mainframe OSes,....
Drivers with a stable API that don't break with each new minor version.