I wasn't only talking about code completion either - when I make any syntax/type error I get a red squiggly after about a second and hovering shows the compiler error (which often has hints for solving it). Same goes for compiler warnings (e.g. green squigglies for dead code). Feels quite close to IntelliJ already (I use PyCharm...).
You can already get instant hints now with VS Code and the Rust Language Server (RLS). It's still in alpha and the initial setup is a bit involved, but it already works very well for me.
For some reason, code completion via Racer doesn't work yet for me via RLS, so I use the "old" RustyCode extension for that (https://github.com/saviorisdead/RustyCode).