Changes like this needs to be discussed in python-ideas first https://mail.python.org/mailman3/lists/python-ideas.python.org/ . The current behavior is as below : 

>>> a, b += 1, 2
  File "<stdin>", line 1
SyntaxError: illegal expression for augmented assignment

See also for some reference to the initial PEP proposal : https://stackoverflow.com/a/18132749/2610955

There is also a comment related to this where this error is raised https://github.com/python/cpython/blob/b9a0376b0dedf16a2f82fa43d851119d1f7a2707/Python/ast.c#L3302

Augmented assignments can only have a name, a subscript, or an
attribute on the left, though, so we have to explicitly check for
those.

I would propose closing this now and reopening this if there is some consensus on moving forward with this in python-ideas.