Well, to start this is the flex-dev mailing list for the Apache Flex project... it is not the Apache Flash Runtime and ActionScript 3 language Project... so not sure why so many people want to come and suggest language enhancements. I understand we all want improvements to ActionScript 3, but that's not what we're doing here. We're here to work on, fix, and improve the Flex SDK.
As far as MXML goes Adobe has stated their intent on donating the MXMLC compiler. This has yet to pass legal review I believe, like the actual SDK source code, and is why we have not yet actually received the compiler code for MXMLC. As far as I understand MXMLC uses the same ActionScript 3 compiler that the Flash Pro IDE uses, except it handles the parsing and conversion of MXML code. If and when the MXMLC compiler is donated we should be able to update how MXML files are handled... however, the Falcon compiler will also eventually be donated (or at least its been stated as an intention) and personally I think any changes we attempt to make to MXML should wait until we have that code for the Falcon compilers (Falcon and FalconJS). As far as AS3 language changes go once we receive all compilers... I still doubt at that point we will make AS3 language changes since at this point we will still be limited to the constraints of the AVM. And without knowing what exactly Falcon handles and how its done its hard to say that we'll even be able to make the most minor aesthetic changes to the AS3 language. In short, I would suggest we all focus our energy on things that we can effect in the immediate future and that which should be our main focus, the Flex SDK. That said, nobody is stopping you from dreaming up a wishlist! -omar