> Which parts of Rust would you give up to make this happen? And how would this be implemented?

Traits, maybe? Switch to an OO model more closely aligned to what the majority of developers understand. Dump all of the line-noise-type syntax.

My Own Toy Language (ComingRealSoonNow)^tm that I started designing had exactly one goal - prevent the majority of memory errors, not prevent ALL memory errors. All I wanted was to indicate when/where an object will be destroyed/mutated. That's enough for me.