That's not an option in practice, since the whole point of going 64 bit is to get larger address spaces. You could define a special purpose ABI with 32-bit poin

That's not an option in practice, since the whole point of going 64 bit is to get larger address spaces. You could define a special purpose ABI with 32-bit pointers and 64-bit integer types (and people have done so). But doing it for the platform's standard ABI would be just commercial suicide.