I think that the "null issue" is not an issue. Strictly speaking if you want null or an int - leave out the type hint and use generic argument that will accept anything. I think it's over-engineering to try and push a special treatment for the null. If function/method argument accepts anything but a single type - it's type-less and does not need a type hint.
Developers should not abuse type hints and adding a special case for handling null will make many start to request things like this: function foo(string|array $data) function foo(bool|int $flag) function foo(mixed $someVar) etc. I'm not sure about you, but I don't wanna see that kind of thing eventually making it's way into the language (believe me - even I considered that at some point, but i'm more mature now and more settled in my wishes :))
