Self and Newspeak sort of do it this way, adding implicit self to Smalltalk's keyword syntax and accessor convention.

These 'accessors' also work on local variables, there is no special syntax for assignment. So when you write x it means send the message x, which starts its lookup in the local environment and works itself outwards. When you write x:2 it sends the message x: with argument 2, also starting in the local environment.

The accessors are automatically generated in pairs for slots. It sorta works, but it seems a bit too convoluted just to say "hey, we can do everything with just messaging".