It looks like we’re going the other way, given that PRO is going to be mostly removed.
I think this could make the language non-ergonomic and has the risk of worsening performance. Values do lead to better optimizations, and they are so much easier to reason about. Most times it’s ok to create a short lived copy that will be restricted in scope, and the compiler can easily optimize this. I think it would be better to improve the algorithms for elliding copies.