Guido, I'm not entirely sure if you're joking or not, but if we'll start with this, we will never finish.
I believe that although str/bytes truly are special regarding iterables, the combinations are endless.
Soon enough we'll have NotBytesSequence, NumericSequenceWithoutFloat and BuiltinNotCustomMadeIterable.
We cannot guarantee a "meaning". We can however guarantee an interface or API, in this case __iter__,
and promote duck-typing in order to support even the craziest custom iterables.
I think breaking the design or the state-of-mind in case of "IterableButNotString" would be a mistake, unless
we're planning to remove str's __iter__ altogether (which I don't support either but who knows).
Nevertheless, +1 for the unification of Iterable, Sized and Container or "Reiterables" as it declares a clearer interface.