I think I'd be happy with a stable API, it wouldn't have to be a stable binary interface. Wanna change the internals of a struct? Totally fine. Not make binary shims for 32-bit drivers? Totally fine.
That would encourage open-source or at least source-available drivers (to allow recompiling for ABI changes), but recompilation should be straightforward and possibly automatic if the API doesn't change every couple months.
> In my opinion, investing in a proper driver architecture with a stable interface would be a massive step toward better Linux hardware support and broader adoption.
Eh, I have mixed feelings about this. Part of what makes Linux so great is that most of its drivers are open source - which allows the devices it supports to stay supported basically forever (though bitrot certainly is a thing). And they achieved this by making maintaining out-of-tree drivers so damn painful.
A stable interface would sort of undermine this. I honestly don't know if that'd be preferable to the status quo.