I think you’re incorrect – this is a pretty serious change to the language (inheritance is much more fundamental to Scala than to Common Lisp), and I suspect it would break a considerable amount of existing code.
But seriously: if you want to push this, the right place is the Contributors forum, not this one – that’s where language-change proposals get seriously discussed. It’s where the folks who actually manage the Scala language mostly hang out, and they’d have a far more informed opinion…