Consider contributing to the RFC process. This has been proposed a number of times, and I don't think anyone's against it. It's just not been considered priority.
I would advise that TCE will probably be more acceptable to the Rust community with an explicit opt-in syntax. And that `become` is a reserved keyword in Rust that is semi-earmarked for this purpose.
I doubt I have the know-how it needs to navigate the issues raised in the previous discussions. I could maybe write a proposal where sibling recursion (i.e. self recursion and calls to equally-typed procedures) is guaranteed via the becomes keyword, but i dont really have the motivation to spend that much time discussing it or write the proposal.
Such a proposal would in any way be "future proof" in the sense that general becomes-TCO could be added later in a compatible way.
I would advise that TCE will probably be more acceptable to the Rust community with an explicit opt-in syntax. And that `become` is a reserved keyword in Rust that is semi-earmarked for this purpose.