It’s memory safety that’s a problem. Just look at the number of crashes and hangs reported to Technical Support over the years. The Rust language, already embraced within the company, can fix these problems. Automated translation of the C source can get 70%-80% of the way and the rest can be done by the new hires familiar with Rust. I know of two or more internal AA proponents of Rust that could orchestrate the transition.
V9 could benefit, too, but its user base is fading away while the user base for Viya is growing (substantially) so the cost/benefit there is more questionable.