_member_() is fine with me, though I prefer _auto_(). _auto_member_() is probably too much. :-)

The argument "we already do magic, so let's do also this bit of non-connected magic" seems very weak to me. But in fact those other things are not _magic_ in the same sense as this one (except repatching __new__, I agree that's weird, but Guido started that game when he declared bool unsubclassable:). They are just added behaviors.

This is something fundamental: it is breaking the promise that class body is a suite of commands, where Python statements (such as assignment) have their usual semantics. If I ever see, in any suite,

    a = x
    b = x

and after that `a is not b`, I feel cheated. Even more strongly: I _don't know how to think about the code_ anymore. Those look like assignment statements, but they are not. What are they? Is this Python?

And what if you really do want to make aliases? Are you saying that

    a = x
    b = a

should be fundamentally different than the above? Oh, please let's not go there. :-)