If this follows the monomorphic approach described in Featherweight Go [1][2], they will at least avoid problems caused by type erasure and avoid too much runtime overhead.
But then you have compile time overhead (an issue Rust and C++ have faced). One of Go's design goals was to have very fast compile times, which might be in doubt if they take the monomorphization approach.
Is rust's slow compile time because of poor LLVM IR generation or just because monomorphization? D has generics and compiles fast. I guess Nim compile times are okay, too..
1. https://arxiv.org/abs/2005.11710 2. https://news.ycombinator.com/item?id=23368453