I think there's no reason not to keep __trunc__ and math.trunc - they're natural counterparts to floor and ceil, and there's probably at least some code out there already using math.trunc.

It's the involvement of __trunc__ in the int() builtin that I'd quite like to deprecate and eventually remove. I think at this point it complicates the object model for no particularly good reason. But this is getting off-topic for this issue; I'll open a new one.